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ScienceCh 12 Electric Current ke Magnetic Effects

Magnetic Effects of Electric Current: Class 10 Science Chapter 12 Hinglish mein

Science · Hinglish notes, simulations aur practice · Official NCERT chapter PDF ↗

Published · Updated

  • 75 min
  • 2 simulations
  • 29 practice questions
  • 20 MCQs

Is chapter mein aap kya seekhenge

  • Magnetic field kya hai samjho, bar magnet ke around field pattern sketch karo aur field lines ki properties batao
  • Seedhi wire, circular loop aur solenoid mein current ka field samjho, aur yeh current, distance aur turns ki sankhya par kaise depend karta hai
  • Current ke around magnetic field ki direction nikaalne ke liye right-hand thumb rule use karo
  • Electromagnet kaise kaam karta hai samjhao aur use permanent magnet se compare karo
  • Magnetic field mein current-carrying conductor par lagne wala force samjhao aur Fleming's left-hand rule se uski direction nikaalo
  • Ghar ki wiring kaise hoti hai, earth wire aur fuse logon ko kaise bachate hain, aur overloading aur short circuit kyun hote hain, yeh samjhao

NCERT Science Class 10, Chapter 12, pp. 195–207 par based original companion text. Yeh NCERT se juda nahi hai aur NCERT ne ise endorse nahi kiya hai.

Pichhle chapter mein tumne dekha ki electric current wire ko garam kar deta hai. Current ek aur kaam bhi karta hai, jo tum haath se mehsoos nahi kar sakte: woh wire ke around ki jagah ko magnetism se bhar deta hai. Scrapyard ki crane ek purani car ko iron ke ek block se uthati hai, jo sirf tab tak magnet hota hai jab tak usmein current behta hai. Tumhare school gate ki bell aur ceiling fan ki motor bhi electricity aur magnetism ke isi rishte par chalti hain.

2/3Current upar tumhari taraf aata hai (dot). Needle east ki taraf ghoomti hai.

Fig. 12.1Wire mein current compass needle ko ghuma deta hai; current ulatne par needle doosri taraf ghoomti hai.NCERT Fig. 12.1 · p. 195

Ek grey card ka top view, jismein se ek khadi wire guzarti hai aur wire se thoda south mein ek compass hai, saath mein north dikhata ek arrow. Step 1: key khuli hai, current nahi hai aur needle north ki taraf point karti hai. Step 2: current card se upar tumhari taraf behta hai, jise circle mein dot se dikhaya gaya hai; wire ke around anticlockwise arrows wala ek dashed circle hai aur needle east ki taraf ghoom jaati hai. Step 3: cells ulat diye gaye hain, current neeche behta hai, jise circle mein cross se dikhaya gaya hai; circle par arrows clockwise point karte hain aur needle west ki taraf ghoom jaati hai.

To current le jaane wali wire ek magnet ki tarah kaam karti hai. Is chapter mein tum magnetic fields ka map banaoge aur wires aur coils ke around unki shape dhoondhoge. Tum dekhoge ki magnet current ko kaise wapas dhakelta hai. Aakhir mein tum woh wiring dekhoge jo ghar tak electricity ko safely laati hai.

12.1 Magnetic Field aur Field Lines

Pichhli classes se tum magnets ka basic rule jaante ho: like poles repel karte hain aur unlike poles attract karte hain. Compass needle (दिक्सूचक सुई) bas ek pin par balanced chhota, halka magnet hai, isliye woh bhi yahi rule maanti hai. Akele chhodne par woh lagbhag north–south line ke along tik jaati hai. Jo sira north ki taraf ghoomta hai woh uska north-seeking end, yaani north pole hai, aur doosra sira uska south pole hai.

Bar magnet ko compass ke paas lao aur needle ghoom jaati hai. Magnet ka north pole needle ke north end ko door dhakelta hai aur uske south end ko paas kheenchta hai. Uska south pole iska ulta karta hai. Yeh dhakke aur khinchaav milkar needle ko tab tak ghumate hain jab tak woh us jagah par magnet ke influence ke along tik nahi jaati.

Pattern dikhata hai ki magnet sirf un cheezon par nahi jinhe woh chhoota hai, balki apne around ki jagah par bhi kaam karta hai. Us jagah ka ek naam hai.

Definition
Magnetic field

Magnet ke around ka woh region jismein uska force detect kiya ja sakta hai, jaise compass needle ya iron filings se. Magnetic field ki strength bhi hoti hai aur direction bhi.

ExampleFridge-door magnet ke around ki woh jagah jismein paper clip khinchti hai.

Filings jo curves banati hain unhe magnetic field lines kehte hain. Yeh field ki picture hain. Kisi bhi point par inki direction batati hai ki wahan field kis taraf point karta hai, aur inki spacing batati hai ki field kitna strong hai.

SimulationBar magnet ke around filings aur compass

Stage ke beech mein ek bar magnet hai aur uske around iron filings mudi hui chains mein faili hain. Ek chhota compass kahin bhi drag kiya ja sakta hai; uski needle us jagah ke field ke hisaab se ghoomti hai. Ek toggle arrows wali field lines dikhata ya chhupata hai, aur doosra filings ko chhupata hai.

Fig. 12.2Compass ko magnet ke around drag karo. Field lines on karke unhe filings se compare karo.
Try karo
  • Compass ko bilkul north pole ke paas rakho. Needle ka kaun sa sira magnet ki taraf point karta hai?
  • Compass ko north pole se dheere-dheere ghuma kar south pole tak le jao aur needle ko ghoomte dekho.
  • Field lines on karo. Kya woh filings ki chains ko follow karti hain?

4/5Dots se guzarti smooth curve ek field line hai, jis par N se S ki taraf arrow hai.

Fig. 12.3Field line plot karna: compass ki har nayi position wahan se shuru hoti hai jahan pichhli needle ka north end point kar raha tha.NCERT Fig. 12.3 · p. 197

Picture ke neeche ke paas ek bar magnet hai, left mein S aur right mein N. Step 1: N end ke theek upar ek compass hai, uski needle magnet se door point karti hai, aur needle ke har sire par ek dot hai. Step 2: compass aage khisak gaya hai taaki uski tail pichhle head dot par aaye, aur ek naya dot uska head mark karta hai; purani position ek dashed circle hai. Step 3: dashed circles aur dots ki ek chain magnet ke upar arch banati hui S end tak jaati hai, jahan aakhri compass neeche S ki taraf point karta hai. Step 4: dots ek smooth blue curve se jude hain jis par N se S ki taraf arrow hai. Step 5: magnet ke upar aur neeche aur blue curves jod di gayi hain, sab N se ghoom kar S tak jaati hain.

Kisi bhi ek field line ko poora ghoom kar follow karo aur tum wahin wapas pahunch jaoge jahan se shuru kiya tha: field lines closed loops hoti hain. Magnet ke bahar loop north pole se ghoom kar south pole tak jaata hai, aur magnet ke andar south pole se wapas north pole tak safar poora karta hai. Arrows ek simple agreement follow karte hain: har point par line us taraf point karti hai jis taraf wahan rakhi compass needle ka north pole point karta.

Tum kabhi do field lines ko cross karte nahi dekhoge. Crossing par compass ko ek saath dono lines ke along line up karna padta, lekin ek needle sirf ek hi taraf point kar sakti hai. Yeh bhi dekho ki poles par lines kaise ikatthi ho jaati hain: lines jitni paas-paas packed hon, us region mein field utna hi strong hota hai.

2/4Andar, woh S se wapas N tak jaati hain, isliye har line ek closed loop hai.

Fig. 12.4Bar magnet ki field lines: closed loops jo kabhi cross nahi karti, aur jahan field strong hai wahan ghani hoti hain.NCERT Fig. 12.4 · p. 197

Beech mein ek bar magnet hai, left mein S aur right mein N, aur uske chaaron taraf blue field lines hain. Step 1: lines N end se nikalti hain, ghoom kar S end mein ghusti hain; arrows N se S ki taraf point karte hain, aur labels par leave N aur enter S likha hai. Step 2: magnet ke andar dashed lines S se N tak jaati hain, jin par inside: S to N likha hai, isliye har line apne aap mein band hoti hai. Step 3: N end ke around ek dotted oval ghane, strong region ko mark karta hai, aur upar ke kone mein ek label door ke faile hue, weak region ko mark karta hai. Step 4: lines fade ho jaati hain aur do purple dashed curves ek point par cross karti hain, jahan do green arrows alag-alag directions mein point karte hain, saath mein note ki compass ek saath do taraf point nahi kar sakta.

Short mein, magnetic field lines:

  • magnet ke bahar north pole se nikalti hain aur south pole mein ghusti hain, aur uske andar south se north ki taraf chalti hain;
  • closed curves banati hain;
  • jahan field zyaada strong hai wahan zyaada paas-paas hoti hain;
  • kabhi ek doosre ko cross nahi karti;
  • kisi bhi point par field ki direction us jagah line ki direction se dikhati hain, yaani jidhar compass needle point karegi.
SimulationDo magnets: lines jo kabhi cross nahi karti

Do bar magnets saath-saath rakhe hain, unke around field lines aur chhote compasses ka ek grid hai. Kisi bhi magnet ko drag kiya aur ghumaya ja sakta hai, aur ek button right wale magnet ke poles flip karta hai. Arrows dikhate hain ki magnets attract kar rahe hain ya repel, aur compass grid har jagah field ki direction dikhata hai.

Fig. 12.5Kisi bhi magnet ko drag karo aur right wale ko flip karo. Lines chahe jaise mudein, woh kabhi cross nahi karti.
Try karo
  • North pole ko south pole ke saamne rakho. Lines sabse zyaada ghani kahan hain?
  • Right wale magnet ko flip karo taaki do north poles aamne-saamne hon. Unke beech lines kaise mudti hain?
Quick check
4 mein se 1
Bar magnet ki ek field line par ek chhota compass rakha hai. Uska north end point karta hai:
Answer dekho

Answer (A) line ke along, jidhar uska arrow point karta hai

Definition ke hisaab se, field line ka arrow batata hai ki compass ka north pole kidhar point karta hai. To needle line ke along rehti hai, aur uska north end arrow ko follow karta hai. Right angles par hona field line ke matlab ke hi khilaaf hoga.
Practice · 4 questions

Practice 12.1 (NCERT in-text questions, pp. 196 aur 200): answers ke saath

  1. Short answerEasyNCERT in-text Questions p. 196, Q1

    Tumhara dost fridge-door magnet ke paas ek compass pakadta hai, aur needle ghoom jaati hai. Samjhao kyun.

    Solution dikhao

    AnswerNeedle khud ek chhota magnet hai, isliye magnet ke poles uske ek sire ko dhakelte hain aur doosre ko kheenchte hain, aur use ghuma dete hain.

    Compass needle ek chhota magnet hai. Paas ka magnet needle ke ek pole ko attract karta hai aur doosre ko repel. Dono siron par opposite directions mein dhakka lagta hai, isliye needle tab tak ghoomti hai jab tak us jagah magnet ke field ke saath line up nahi ho jaati.

  2. DiagramEasyNCERT in-text Questions p. 200, Q1

    Ek bar magnet aise rakha hai ki uska north pole east ki taraf point karta hai. Uske around kam se kam chhe field lines arrows ke saath sketch karo.

    Solution dikhao

    AnswerCurves east (N) end se nikalti hain, upar aur neeche ghoom kar west (S) end mein ghusti hain; bahar arrows N se S ki taraf chalte hain.

    1. Magnet aise banao ki N east (right) side par ho aur S west par.
    2. Aisi curves banao jo N end se shuru hon, magnet ke upar aur neeche ghoomein, aur S end par khatam hon. Teen upar aur teen neeche banao, andar wali chhoti aur bahar wali badi.
    3. Poles ke paas lines paas-paas rakho aur magnet se door zyaada doori par.
    4. Har line par N se S ki taraf point karta arrow lagao. Agar magnet ke andar bhi lines banate ho, to unke arrows S se N ki taraf point karte hain.
  3. Short answerEasyNCERT in-text Questions p. 200, Q2

    Magnetic field lines ki chaar properties likho.

    Solution dikhao

    AnswerWoh bahar N se S aur andar S se N jaati hain; woh closed curves hain; jahan field strong hai wahan zyaada paas hoti hain; woh kabhi cross nahi karti.

    • Magnet ke bahar woh north pole se south pole ki taraf jaati hain; andar south se north ki taraf.
    • Woh closed curves hoti hain.
    • Jahan field strong hai wahan ghani hoti hain aur jahan weak hai wahan phaili hui.
    • Koi do field lines kabhi cross nahi karti.
  4. Short answerMediumNCERT in-text Questions p. 200, Q3

    Maan lo do field lines ek point X par cross karti. X par rakhe compass ko kya karna padta? Isse samjhao ki field lines kabhi cross kyun nahi karti.

    Solution dikhao

    AnswerUse ek saath dono lines ke along point karna padta, jo impossible hai, isliye kisi point par field ki sirf ek direction hoti hai aur lines cross nahi kar sakti.

    Kisi point par field line ki direction woh direction hai jidhar wahan compass needle point karti hai. Crossing point par do alag directions hoti, to needle ko ek hi time par do taraf point karna padta. Needle sirf ek direction mein point kar sakti hai, isliye kisi bhi point par field ki bas ek direction hoti hai, aur do field lines kabhi cross nahi kar sakti.

12.2 Current-Carrying Conductor ke kaaran Magnetic Field

Activity 12.1 ne dikhaya ki current ek magnetic field banata hai. Ab do sawaal uthte hain: us field ki shape kya hai, aur woh kis taraf point karta hai? Jawab is baat par depend karta hai ki wire kaise mudi hai, isliye hum ek-ek karke teen shapes dekhenge: seedhi wire, ek single circular loop aur ek lambi coil.

12.2.1 Seedhe Conductor mein Current ke kaaran Magnetic Field

Sabse simple shape se shuru karo, ek lambi seedhi wire. Pehle hum pata karenge ki uske field ki direction current par kaise depend karti hai.

2/4Wire upar, current south se north: north end west ki taraf ghoomta hai.

Fig. 12.6Current ulatne par needle ka ghoomna ulat jaata hai, aur tab bhi jab wire compass ke upar se neeche chali jaati hai.NCERT Fig. 12.5 · p. 198

Upar se dekha gaya ek bada compass, jiske across ek wire south (neeche) se north (upar) tak seedhi jaati hai, aur north dikhata ek arrow. Step 1: current nahi; needle wire ke along north ki taraf point karti hai. Step 2: wire compass ke upar hai aur orange arrows south se north current dikhate hain; needle ka north end west, yaani left ki taraf ghoom gaya hai. Step 3: arrows north se south point karte hain aur needle east, yaani right ki taraf ghoom gayi hai. Step 4: wire dashed banayi gayi hai yeh dikhane ke liye ki woh compass ke neeche hai, current phir se south se north hai, aur needle east ki taraf ghoomti hai.

Ab hum field ki shape ka map banayenge aur dekhenge ki uski strength kaise badalti hai.

2/4Current card se upar (dot): filings rings banati hain; needles ghoomti hain, P zyaada, Q kam.

Fig. 12.7Seedhi wire ke around field lines circles hoti hain. Paas wala compass P, Q se zyaada ghoomta hai, aur current double karne par dono aur zyaada ghoomte hain.NCERT Fig. 12.6 · p. 199

Upar se dekha gaya ek grey card, jiske beech mein ek wire hai, wire ke around chaar blue circles hain, aur uske south mein do chhote compasses P (paas) aur Q (door) hain; ek arrow north mark karta hai. Step 1: current nahi; chhoti filings bikhri padi hain aur dono needles north ki taraf point karti hain. Step 2: current upar tumhari taraf aata hai (dot); filings circles ke along line up hoti hain, circles par arrows anticlockwise chalte hain, aur needles east ki taraf ghoomti hain, P lagbhag 63 degrees aur Q lagbhag 42 degrees. Step 3: current double kiya jaata hai aur needles aur ghoomti hain, P lagbhag 76 degrees tak aur Q lagbhag 61 degrees tak. Step 4: current ulat diya jaata hai (cross); circles par arrows clockwise chalte hain aur dono needles iske bajaay west ki taraf ghoomti hain.

Activity se teen results milte hain jo yaad rakhne laayak hain. Seedhi wire ki field lines concentric circles hoti hain, jinka centre wire par hai, aur jo wire ke right angles wale planes mein hoti hain. Kisi diye gaye point par current badhne se field zyaada strong hota hai. Aur fixed current ke liye, wire se jitna door jaao field utna weak hota jaata hai. Isiliye Fig. 12.7 mein bane circles jitne bade hote hain, utne hi door-door hote jaate hain.

Lambi seedhi wire ka field
B∝Ir
(12.1)
jahan
B
kisi point par magnetic field ki strength
I
wire mein current
r
wire se point ki doori

To current double karne se kisi point par field double ho jaata hai, aur do guna door jaane se aadha. (Compass readings mein needle Earth ka field bhi mehsoos karti hai, isliye angle seedha double nahi hota.)

12.2.2 Right-Hand Thumb Rule

Wire ke around field kis taraf ghoomta hai, yeh jaanne ke liye har baar compass ki zaroorat nahi. Tumhara right hand kaafi hai.

Definition
Right-hand thumb rule

Wire ko right hand se aise pakdo ki tumhara thumb uske along current ki direction mein point kare. Tumhari mudi hui ungliyan wire ke around jis taraf lipatti hain, field lines usi taraf ghoomti hain.

3/4Field wire ke around usi taraf ghoomta hai jidhar ungliyan mudti hain: upar se dekhne par anticlockwise.

Fig. 12.8Right-hand thumb rule: thumb current ke along, ungliyan field ki direction mein mudti hain.NCERT Fig. 12.7 · p. 200

Ek khadi copper-coloured wire jiske upar orange arrow par current likha hai. Step 1: sirf wire aur upar jaata current. Step 2: right hand ki muththi wire ko pakadti hai, haath ki peeth ki taraf se dekhi gayi, thumb wire ke along upar point karta hai aur chaaron ungliyan wire ke aage se left se right lipti hain; ek label par thumb points along the current likha hai. Step 3: muththi ke upar aur neeche do blue ellipses wire ko gher rahe hain; unke aage wale half par arrows right aur peechhe wale half par left point karte hain, jo upar se dekhne par anticlockwise hai, ungliyon ke mudne se match karta hua. Step 4: current arrow neeche point karta hai, muththi palat di gayi hai aur thumb neeche hai, aur circles ke arrows ulat gaye hain.

Rule ko Activity 12.5 par test karo, jahan current card se upar tumhari taraf aaya tha. Apna right thumb apne chehre ki taraf karo: tumhari ungliyan anticlockwise mudti hain, bilkul Fig. 12.7 ki rings ke arrows ki tarah.

Example 12.1NCERT Example 12.1 · p. 200

Gali ke upar ek cable

Steady current le jaane wali ek lambi seedhi cable ek north–south gali ke along horizontally lagi hai, aur usmein current south se north behta hai. Cable ka magnetic field kis taraf point karta hai (a) cable ke theek neeche ke point par, (b) uske theek upar ke point par?

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Quick check
4 mein se 1
Ek lambi vertical wire mein current neeche ki taraf behta hai. Upar se dekhne par uski field lines ghoomti hain:
Answer dekho

Answer (B) clockwise

Upar se dekhne par current tumse door beh raha hai, isliye thumb rule (ya corkscrew rule) se field lines clockwise ghoomti hain. Anticlockwise jawab upar behte current ke liye hota.

12.2.3 Circular Loop mein Current ke kaaran Magnetic Field

Ab seedhi wire ko ek circle mein modo aur uske around current chalao. Uska field kaisa dikhta hai? Wire ke bilkul paas zoom karo to loop ka koi bhi chhota hissa seedha dikhta hai, isliye wire ke paas field lines uske around chhoti rings hoti hain, bilkul Fig. 12.7 ki tarah.

Socho ki loop ko uske centre se aadha kaata gaya hai, jaise Fig. 12.9 mein. Current upar (A) par page se bahar aata hai aur neeche (B) par andar jaata hai. Thumb rule pehle A par aur phir B par lagao: dono loop ke beech se same direction mein point karta field dete hain. Loop ka har hissa isi tarah andar ke field mein jodta hai. To, halaanki lines wire ke around kas kar mudti hain, centre ke paas field strong hota hai aur uski lines lagbhag seedhi aur parallel hoti hain.

3/4Aur bahar circles chaude hote hain; centre par lines lagbhag seedhi hain aur sab same taraf point karti hain.

Fig. 12.9Circular loop ki field lines, uske centre se kaate gaye section mein. Loop ke andar wire ka har hissa field ko same taraf dhakelta hai.NCERT Fig. 12.8 · p. 200

Ek circular loop jo lagbhag kinare se dikhta hai, ek patle orange ellipse ki tarah; uska upar ka crossing A dot se mark hai (current page se bahar) aur neeche ka crossing B cross se (current page ke andar); orange arrows loop ke around chalta current dikhate hain. Step 1: sirf loop aur A aur B ke labels. Step 2: A aur B ke around chhote band blue circles hain; A ke around arrows anticlockwise aur B ke around clockwise chalte hain, aur loop ke andar arrows right ki taraf point karte hain. Step 3: aur badi lines jodi jaati hain; woh upar aur neeche bahar ki taraf phoolti hain aur centre ke paas lagbhag seedhi ho jaati hain, sab right ki taraf point karti hui, aur ek seedhi line axis ke along hai. Step 4: beech mein extra lines bhar di jaati hain, jo dikhati hain ki n turns wali coil n guna strong field deti hai.

Ab wire ko ek baar ki jagah kai baar lapeto. n turns ke saath same current same direction mein n baar ghoomta hai, aur har turn centre ke field mein apna hissa jodta hai. Field single turn ke field ka n guna ho jaata hai, isliye tum turns badha kar ya current badha kar use strong kar sakte ho.

12.2.4 Solenoid mein Current ke kaaran Magnetic Field

Insulated wire ke kai turns saath-saath lapeto, jaise reel par dhaaga, aur tumhe ek solenoid (परिनालिका) milta hai. Saare turns ke fields jud jaate hain, aur jo pattern banta hai use tum pehle hi dekh chuke ho.

Definition
Solenoid

Insulated wire ki ek lambi, kas kar lapeti coil jismein kai turns hon, aur jiski shape tube jaisi ho.

3/4Bahar lines ek end se ghoom kar doosre end tak jaati hain, aur ends N aur S poles ki tarah kaam karte hain.

Fig. 12.10Solenoid ka field: andar uniform, bahar bar magnet jaisa. Jis end se lines nikalti hain woh north pole ki tarah kaam karta hai.NCERT Fig. 12.10 · p. 201

Ek lamba solenoid jo uski length ke along kaata gaya hai: upar dots ki ek row (current page se bahar) aur neeche crosses ki ek row (current page ke andar), aur tube ki dashed outline. Step 1: sirf coil, aur dono rows ke labels. Step 2: tube ke andar blue lines left se right seedhi, parallel aur barabar doori par chalti hain, jin par parallel and evenly spaced likha hai. Step 3: bahar lines right end se nikalti hain, upar aur neeche ghoomti hain, aur left end mein ghusti hain; right end par N aur left end par S mark hai. Step 4: coil ke upar same size ki ek dashed purple bar-magnet outline rakhi gayi hai, saath mein note ki pattern bar magnet jaisa hi hai.

Is picture ko Fig. 12.4 ke bar magnet ke saath rakho, aur coil ke bahar dono mein farak karna mushkil hoga: coil ka ek end north pole ki tarah aur door wala end south pole ki tarah kaam karta hai. Kaun sa end kaun sa hai, yeh jaanne ke liye kisi end par clock rule lagao. Ya apne right hand ki ungliyan us taraf modo jidhar current turns mein ghoomta hai: tab tumhara thumb north end ki taraf point karta hai.

Lambe solenoid ke andar field lines seedhi, parallel aur barabar doori par hoti hain. Iska matlab hai ki andar har point par field ki strength aur direction same hai: yeh ek uniform magnetic field hai.

Definition
Uniform magnetic field

Aisa magnetic field jiski kisi region ke har point par strength aur direction same ho. Iski field lines seedhi, parallel aur barabar doori par hoti hain.

Solenoid ke andar ka strong field usmein rakhi iron ya steel ki bar ko magnet bana sakta hai. Solenoid ke andar soft iron ki bar use electromagnet (विद्युत चुंबक) bana deti hai.

Definition
Electromagnet

Insulated wire ki current-carrying coil ke andar soft iron rakh kar banaya gaya magnet. Yeh sirf tab tak magnetic rehta hai jab tak current behta hai.

2/4Coil mein current core ko magnetise kar deta hai, jo pins utha leta hai.

Fig. 12.11Soft iron sirf current behne tak magnet rehta hai; steel apna kuch magnetism bachaa kar rakhta hai.NCERT Fig. 12.11 · p. 201

Orange coil se lapeti ek horizontal bar, jo wires se neeche ek cell aur key se judi hai, aur right mein pins ki ek tray hai. Step 1: key khuli hai aur pins tray mein padi hain; bar par soft iron core likha hai. Step 2: key band hai, orange arrows current dikhate hain, aur bar ke right end se kai pins latki hain. Step 3: key phir khuli hai aur saari pins wapas tray mein gir gayi hain. Step 4: ab bar par steel rod core likha hai; key khuli hai, phir bhi do pins usse chipki hain aur baaki tray mein padi hain.

Compare

Electromagnet ya permanent magnet?

Electromagnet

  • Sirf current behne tak magnetic
  • Strength current aur turns ki sankhya ke saath badalti hai
  • Current ulatne par poles badal jaate hain
  • Aam taur par soft iron core hota hai

Permanent magnet

  • Hamesha magnetic
  • Strength fixed hoti hai
  • Poles fixed hote hain
  • Steel ya alnico jaise special alloys se bana
Quick check
4 mein se 1
Tumhari desk par ek flat coil padi hai. Upar se dekhne par current anticlockwise ghoomta dikhta hai. Coil ke andar field point karta hai:
Answer dekho

Answer (C) seedha upar, tumhari taraf

Anticlockwise current us face ko north pole bana deta hai jise tum dekh rahe ho, isliye andar ka field upar tumhari taraf aata hai. Clockwise current use neeche desk ke andar bhejta.
Practice · 3 questions

Practice 12.2 (NCERT in-text questions, pp. 201–202): answers ke saath

  1. Short answerMediumNCERT in-text Questions p. 201, Q1

    Wire ka ek circular loop table par flat pada hai. Upar se dekhne par current uske around anticlockwise ghoomta hai. Right-hand thumb rule se magnetic field ki direction nikaalo (a) loop ke andar, (b) uske theek bahar.

    Solution dikhao

    Answer(a) Vertically upar, table se bahar. (b) Vertically neeche, table ke andar.

    Upar se dekhne par loop ke tumhare sabse paas wale hisse mein current left se right behta hai. Apna right thumb us taraf karo: tumhari ungliyan loop ke centre wali side par upar aati hain aur bahar wali side par neeche jaati hain.

    To loop ke andar field vertically upar, table se bahar point karta hai, aur loop ke theek bahar vertically neeche point karta hai. Loop ka har hissa yahi result deta hai, aur clock rule bhi yahi kehta hai: anticlockwise face north pole hota hai.

  2. DiagramEasyNCERT in-text Questions p. 201, Q2

    Aise region ko dikhane ke liye tum field lines kaise banaoge jismein magnetic field ki strength aur direction har jagah same ho? Ek jagah ka naam batao jahan aisa field milta hai.

    Solution dikhao

    AnswerSeedhi, parallel, barabar doori wali lines jinke saare arrows same taraf point karein; lambe solenoid ke andar.

    Seedhi lines banao, sab ek doosre ke parallel aur barabar doori par, aur har arrow same taraf point kare. Barabar spacing barabar strength dikhati hai, aur parallel lines same direction. Aisa uniform field lambe current-carrying solenoid ke andar, uske ends se door, milta hai.

  3. Quick answerMediumNCERT in-text Questions p. 202, Q3

    Point X ek lambe current-carrying solenoid ke beech ke paas uske axis par hai. Point Y bhi uske andar hai, ends se utni hi doori par, lekin windings ke paas. X ki tulna mein Y par field hai:

    Answer dekho

    Answer (C) same

    Lambe solenoid ke andar field uniform hota hai: har point par same, chahe axis ke paas ho ya windings ke paas.

12.3 Magnetic Field mein Current-Carrying Conductor par Force

Har push ka ek partner hota hai. Newton's third law kehta hai ki agar ek body doosri ko push karti hai, to doosri bhi utne hi zor se opposite direction mein wapas push karti hai. Humne current ko compass needle push karte dekha hai, isliye needle ka magnet bhi current ko wapas push karta hoga. André-Marie Ampère (1775–1836), woh French scientist jinke naam par current ki unit rakhi gayi hai, ne yahi argument diya. To jo wire hilne ke liye free hai, use hilna chahiye.

2/5Current page se bahar (dot): rod right ki taraf dhakeli jaati hai.

Fig. 12.12Sire se dekhne par rod side mein dhakeli jaati hai: force current aur field dono ke right angles par hai.NCERT Fig. 12.12 · p. 202

Ek horseshoe magnet side par pada hai aur uska mod left mein hai; upar wali bhuja N mark wale pole par aur neeche wali S mark wale pole par khatam hoti hai, aur unke beech blue arrows neeche point karte hain. Ek rod, jo sire se ek chhote circle ki tarah dikhti hai, upar ki ek bar se wire par latki hai taaki woh poles ke beech rahe. Step 1: current nahi; rod seedhi latki hai. Step 2: ek dot tumhari taraf current dikhata hai, rod right ki taraf jhoolti hai aur ek green arrow right point karta hai. Step 3: ek cross tumse door current dikhata hai aur rod left ki taraf jhoolti hai. Step 4: poles badal diye gaye hain, S upar aur N neeche, field arrows upar point karte hain, current phir tumhari taraf hai aur rod left jhoolti hai. Step 5: pehle magnet aur tumhari taraf bade current ke saath rod aur zyaada right jhoolti hai aur green arrow lamba hai.

To rod par force do directions par depend karta hai: current ki aur field ki. Kisi ek ko ulat do to force ulat jaata hai; dono ko ulat do to woh jaisa tha waisa hi rehta hai. Experiments yeh bhi dikhate hain ki push sabse bada tab hota hai jab current field ke right angles par ho. Rod ko aise ghumao ki woh field lines ke along ho jaaye, aur force bilkul gayab ho jaata hai.

Jab current aur field right angles par cross karte hain, to push dono mein se har ek ke right angles par nikalta hai. Ek box ke kone ko socho, jahan teen edges milte hain, har ek baaki do ke square par. Left hand wala ek rule yaad rakhne mein madad karta hai ki kaun sa edge kya hai.

Definition
Fleming's left-hand rule

Apne left hand ke thumb aur pehli do ungliyon ko ek doosre ke right angles par rakho, jaise box ke kone ke edges. First finger field dikhaye aur second finger current. Tab thumb conductor par force dikhata hai, yaani woh jis taraf hilta hai.

1/3First finger field ke along, second finger current ke along, thumb force deta hai.

Fig. 12.13Fleming's left-hand rule: first finger se field, second finger se current, thumb se force.NCERT Fig. 12.13 · p. 203

Ek left hand jiski hatheli tumhari taraf hai aur kalai left mein. Step 1: forefinger right point karti hai, uske saath field likha blue arrow hai; thumb upar point karta hai, uske saath force (motion) likha green arrow hai; middle finger seedha tumhari taraf point karti hai, sire se dikhayi gayi, aur uske saath current, towards you likha dot symbol hai; aakhri do ungliyan mudi hui hain. Step 2: haath fade ho jaata hai aur ek point par sirf teen arrows bachte hain: field right, force upar aur current page se bahar, jin par first finger, thumb aur second finger likha hai. Step 3: yahi teen directions Activity 12.7 se match karne ke liye ghumayi jaati hain: field neeche, current tumhari taraf, aur force right.

InteractiveDirection lab

Teen tabs wala ek interactive direction finder. Force tab mein tum field ki direction aur current, proton ya electron ki direction, har ek ke liye chhe buttons (right, left, up, down, page se bahar, page ke andar) mein se chunte ho; ek diagram field, chalta charge aur green force arrow dikhata hai, aur ek sentence force ki direction batata hai ya kehta hai ki motion field ke along ho to koi force nahi. Field tab mein tum seedhi wire mein current ki direction aur wire ki woh side chunte ho jahan point P hai; diagram P par field ki direction dikhata hai. Quiz tab dono tarah ke random questions deta hai, chhe answer buttons ke saath, galat try ke baad hint, do tries ke baad answer, aur chalta hua score.

Fig. 12.14Force dekhne ke liye ek field aur ek current, ya chalta proton ya electron chuno. Wire ke field ke liye thumb rule par switch karo, ya quiz se khud ko test karo.
Example 12.2NCERT Example 12.2 · p. 203

Electron beam ko modna

Electrons ka ek beam page ke across left se right jaata hai aur seedha page ke andar point karte magnetic field se guzarta hai. Beam kis taraf dhakela jaata hai: (a) page mein upar, (b) page mein neeche, (c) page ke andar, ya (d) page se bahar?

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Quick check
4 mein se 1
Current le jaane wali ek seedhi wire magnet ki field lines ke along padi hai. Us par force hai:
Answer dekho

Answer (B) zero

Force sabse bada tab hota hai jab current field ke right angles par ho, aur zero jab field ke along ho. Sabse bada woh case hai jab wire field lines ke across ho.
Practice · 3 questions

Practice 12.3 (NCERT in-text questions, pp. 203–204): answers ke saath

  1. Quick answerMediumNCERT in-text Questions p. 203, Q1

    Ek electron uniform magnetic field mein, field ke right angles par, free hokar chalta hai. Chalte hue inmein se kya badal sakta hai? Jitne sahi hon sab chuno.

    Saare sahi options chuno
    Answer dekho
    Answer
    • (C) uski motion ki direction
    • (D) uska momentum
    Magnetic force hamesha motion ke right angles par hota hai, isliye woh electron ko tez ya dheema kiye bina uska path mod deta hai. Uski motion ki direction (velocity) badalti hai, aur uska momentum bhi, jo velocity ke along point karta hai. Uski speed, aur isliye uski kinetic energy, same rehti hai, aur uska mass bhi.
  2. Short answerEasyNCERT in-text Questions p. 204, Q2

    Activity 12.7 mein rod ka jhoolna kaise badlega agar:

    1. rod mein current kam kar diya jaaye?

      Solution dikhao

      AnswerJhoola chhota ho jaata hai.

      Kam current kam force deta hai, isliye rod kam doori tak jhoolti hai.

    2. kamzor horseshoe magnet use kiya jaaye?

      Solution dikhao

      AnswerJhoola chhota ho jaata hai.

      Weak field same current par kam force deta hai, isliye jhoola chhota hota hai.

    3. chhoti rod use ki jaaye, taaki uska kam hissa poles ke beech ho?

      Solution dikhao

      AnswerJhoola chhota ho jaata hai.

      Rod ka sirf woh hissa dhakela jaata hai jo field ke andar hai. Field mein kam length ka matlab kam total force aur chhota jhoola.

  3. Quick answerHardNCERT in-text Questions p. 204, Q3

    East ki taraf jaata electrons ka ek beam magnetic field se south ki taraf mud jaata hai. Field kis taraf point karta hai?

    Answer dekho

    Answer (B) neeche ki taraf

    Current electrons ke ulta hota hai, isliye woh west behta hai, aur force south ki taraf hai. Left hand try karo: second finger west, thumb south; tab first finger vertically neeche point karti hai. North aur west bahar ho jaate hain, kyunki field current aur force dono ke right angles par hona chahiye.

12.4 Domestic Electric Circuits

Indian gharon mein electricity alternating current (AC) hoti hai: yeh har second 50 complete cycles (50 Hz) mein aage-peechhe behti hai, aur supply voltage 220 V hota hai. Yeh street se poles par lagi ya zameen ke neeche bichhi cables se aati hai. Main kaam do wires karti hain. Live wire high potential par hoti hai; purane colour code mein iska insulation red hota hai. Neutral wire, jiska insulation black hota hai, earth ke potential ke kareeb rehti hai. 220 V supply in dono ke beech ka potential difference hai.NCERT live aur neutral wires ko positive aur negative bhi kehta hai. AC mein, sahi mein, live wire neutral ke upar aur neeche jhoolti hai, ek second mein 50 cycles.

Definition
Live wire

High potential wali mains wire, neutral wire ke relative 220 V; purane Indian colour code mein red insulation.

Definition
Neutral wire

Mains supply ki return wire, jo earth ke potential ke kareeb rakhi jaati hai; purane colour code mein black insulation.

Meter board par supply sabse pehle electricity board ke lagaye fuse se guzarti hai. Phir aata hai electricity meter, jo tumhari use ki energy record karta hai, aur main switch, jo fuse box (distribution box) tak jaata hai. Wahan se yeh alag-alag circuits mein bant jaati hai, har ek ka apna fuse hota hai. 5 A circuit LED lights, tube lights, fans aur phone chargers ko supply deta hai. 15 A circuit bade current lene wale appliances, jaise geysers, room heaters, washing machines aur air conditioners, ko supply deta hai.

Teesri wire, earth wire, ka insulation green hota hai. Yeh ghar ke paas geeli zameen mein gehre gaade gaye ek mote metal plate se judi hoti hai.

Definition
Earth wire

Green insulation wali ek safety wire jo appliances ki metal bodies ko zameen mein gaade gaye metal plate se jodti hai.

4/4Earth wire geyser aur iron ki metal bodies ko zameen ki plate se jodti hai.

Fig. 12.15Ghar ke andar: fuse box se do circuits, appliances parallel mein, metal bodies earthed.NCERT Fig. 12.15 · p. 205

Left mein live wire L aur neutral wire N chaar boxes se neeche jaati hain: board fuse, meter, main switch aur fuse box. Step 1: sirf yeh column dikhaya gaya hai. Step 2: fuse box se right ki taraf rails ke do pairs nikalte hain: 5 A pair jis par lights and fans likha hai, aur 15 A pair jis par geyser, iron likha hai; har pair mein upar live rail aur neeche neutral rail hai. Step 3: appliances rails ke beech rungs ki tarah dikhte hain, har ek ki live side par switch hai: 5 A circuit par do bulbs aur ek fan, 15 A circuit par ek geyser aur ek iron. Step 4: ek dashed green earth wire neeche ke along zameen mein gaade plate tak jaati hai aur geyser aur iron ki bodies se judi hai.

Har circuit mein appliances parallel mein jude hote hain, har ek live aur neutral wires ke beech pul banata hai (Fig. 12.15). Isse har appliance ko same 220 V milta hai, har ek ko alag se on ya off kiya ja sakta hai, aur ek kharab ho jaaye to baaki chalte rehte hain. Switches aur fuses hamesha live wire mein lagaye jaate hain, taaki off hone par appliance high potential se kat jaaye.

Earth wire ki zaroorat kyun hai? Kai appliances, jaise washing machines, room heaters, steel ki electric kettles aur refrigerators, ki metal bodies hoti hain. Agar andar ka insulation ghis jaaye, to live wire body ko chhoo sakti hai, aur tab body 220 V par aa jaati hai. Jo bhi use chhoota hai, woh current ko apni body se zameen tak ka raasta de deta hai aur use zor ka shock lagta hai. Agar body earth wire se judi ho, to current iske bajaay is low-resistance raaste se zameen mein chala jaata hai. Body earth ke potential par rehti hai, isliye use chhoona safe hai. Jo bada current behta hai woh aam taur par fuse ko pighla deta hai aur supply kaat deta hai.

3/3Earth wire current ko zameen tak le jaati hai, fuse pighal jaata hai, aur insaan safe rehta hai.

Fig. 12.16Metal body earthed ho to fault current kisi insaan se guzarne ke bajaay zameen mein jaata hai aur fuse uda deta hai.NCERT Earth wire (text) · p. 204

Left mein ek wall socket, jisse live aur neutral wires ek electric iron tak jaati hain; live wire mein ek fuse hai, aur right mein ek insaan khada hai jiska ek haath iron ki metal body par hai. Step 1: orange arrows dikhate hain ki current live wire ke along andar jaata hai, heating element se guzarta hai aur neutral ke along wapas aata hai; iron normal kaam karta hai. Step 2: andar ki ek dheeli live wire metal body ko chhoo leti hai; ek dashed orange raasta body se insaan ke haath aur pair se hokar zameen tak jaata hai, jis par shock likha hai. Step 3: ab ek dashed green earth wire body ko zameen ki ek plate se jodti hai; ek arrow fault current ko usmein neeche behta dikhata hai, fuse pighla hua dikhaya gaya hai, aur insaan par safe likha hai.

Doosra safety device hai fuse, jise tum pichhle chapter mein dekh chuke ho. Yeh low melting point wali wire ka ek chhota tukda hai, jo live wire mein series mein juda hota hai. Agar current bahut bada ho jaaye, to Joule heating fuse wire ko pighla deti hai aur wiring ya appliances ke kharab hone ya aag pakadne se pehle circuit tod deti hai.

Zyaada current do kaaranon se beh sakta hai. Overloading tab hoti hai jab circuit se uski design se zyaada current le jaane ko kaha jaata hai. Ek circuit par, ya multi-plug adapter se ek socket par, bahut saare appliances chal rahe ho sakte hain, ya supply voltage achaanak badh sakta hai. Short circuit sabse extreme case hai: live aur neutral wires seedhe ek doosre ko chhoo leti hain, jaise jahan cord ka insulation phat gaya ho ya appliance ke andar kuch dheela ho gaya ho. Raaste ka resistance lagbhag zero ho jaata hai, aur current bahut zyaada badh jaata hai.

Definition
Overloading

Circuit se uski design se zyaada current lena, jaise ek saath bahut saare appliances chala kar.

Definition
Short circuit

Aisa fault jismein live aur neutral wires seedhe ek doosre ko chhoo leti hain. Resistance lagbhag zero ho jaata hai, isliye bahut bada current behta hai.

Circuit overloaded hai ya nahi, yeh check karne ke liye pichhle chapter ke P=VI se har appliance ki power rating se uska current nikaalo.

Appliance dwara liya gaya current
I=PV
(12.2)
jahan
P
appliance ki power rating, watts mein
V
supply voltage, Indian gharon mein 220 V
I
woh jitna current leta hai, amperes mein

Kyunki appliances parallel mein hain, unke currents circuit ki live wire aur fuse mein jud jaate hain (Fig. 12.17).

3/41000 W ke heater ke saath 18.2 A behta hai: circuit overloaded hai aur fuse pighal jaata hai.

Fig. 12.17Appliances jodne se current judta hai. 15 A ke paar fuse pighal jaata hai; short circuit current ko scale se bahut aage bhej deta hai.

0 se 25 A tak padhne wala ek gol ammeter dial, jismein 15 A ke upar ka hissa mote orange arc se mark hai; uske paas ek 15 A fuse aur total current ke saath appliances ki list. Step 1: 2000 W geyser on hai; needle 9.1 A padhti hai aur fuse theek hai. Step 2: 1000 W iron joda jaata hai; needle 13.6 A tak jaati hai, abhi bhi 15 A se kam. Step 3: 1000 W heater joda jaata hai; needle 18.2 A tak pahunchti hai, orange zone ke andar, jis par more than 15 A likha hai, aur fuse pighla hua dikhaya gaya hai. Step 4: short circuit, live neutral ko chhoo raha hai; appliance list fade ho jaati hai, needle 25 A ke paar apne stop tak dhakel di jaati hai, current par huge likha hai aur fuse pighla hua hai.

Example

Kya fuse tikega?

Ek family ka 15 A circuit, 220 V par, 2.2 kW ka geyser chalata hai. Woh ek saath 1.1 kW ka microwave oven aur 1.2 kW ki electric kettle bhi chalana chahte hain. Total current nikaalo. Kya 15 A fuse tikega?

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Quick check
4 mein se 1
Ghar mein appliances parallel mein kyun jode jaate hain?
Answer dekho

Answer (A) Taaki har ek ko poora supply voltage mile aur use alag se on kiya ja sake

Parallel mein har appliance poore 220 V ke across hota hai aur uska apna switch hota hai. Har ek mein same current series circuit mein hota, jahan ek fault sab kuch band kar deta.
Practice · 3 questions

Practice 12.4 (NCERT in-text questions, p. 205): answers ke saath

  1. Short answerEasyNCERT in-text Questions p. 205, Q1

    Ghar ki wiring ke do arrangements ke naam batao jo logon ya appliances ko bachate hain, aur ek line mein batao ki har ek kya karta hai.

    Solution dikhao

    AnswerFuse (ya MCB) current bahut bada hone par supply kaat deta hai; earth wire metal body se leakage current ko safely zameen tak le jaati hai.

    • Fuse ya MCB: current bahut bada hone par circuit tod deta hai, jaise overloading ya short circuit mein.
    • Earth wire: appliances ki metal bodies ko zameen se jodti hai, taaki fault current kisi insaan se guzarne ke bajaay earth mein jaaye.
  2. NumericalMediumNCERT in-text Questions p. 205, Q2

    1.5 kW ka room heater 220 V par 5 A lighting circuit ke socket mein lagaya jaata hai. Woh kitna current leta hai nikaalo, aur batao kya hoga.

    A
    Solution dikhao

    I=P/V=1500/220≈6.8 A. Yeh circuit ki design wale 5 A se zyaada hai, isliye circuit overloaded hai. Fuse pighal jaata hai (ya MCB trip ho jaata hai) aur heater band ho jaata hai. Agar fuse bahut mota hota, to wires zyaada garam ho sakti thi. Heater ki sahi jagah 15 A circuit hai.

  3. Short answerEasyNCERT in-text Questions p. 205, Q3

    Teen cheezein likho jo ek family apne ghar ke circuits ko overload hone se bachane ke liye kar sakti hai.

    Solution dikhao

    AnswerEk circuit par kai heavy appliances ek saath mat chalao; ek socket par multi-plug adapters se bacho; sahi rating ke fuses ya MCBs use karo.

    • Ek hi circuit par kai high-power appliances (geyser, heater, iron, cooker) ek saath on mat karo.
    • Multi-plug adapter se ek socket mein kai appliances mat lagao.
    • Sahi rating ke fuses ya MCBs use karo, aur heavy appliances ko 15 A circuit par lagao.
Recap

Summary aur key points

  1. Compass needle ek chhota magnet hai; jo sira north ki taraf point karta hai woh uska north pole hai (Section 12.1).
  2. Magnetic field magnet ke around ka woh region hai jismein uska force detect kiya ja sakta hai; iski strength aur direction dono hoti hain (Section 12.1).
  3. Field lines field dikhati hain: woh us taraf point karti hain jidhar compass ka north pole point karta hai, closed loops banati hain, jahan field strong hai wahan ghani hoti hain aur kabhi cross nahi karti (Section 12.1).
  4. Electric current ek magnetic field banata hai jiska pattern conductor ki shape par depend karta hai (Section 12.2).
  5. Seedhi wire ke around field lines concentric circles hoti hain; field current ke saath badhta hai aur doori ke saath weak hota hai (Section 12.2.1).
  6. Right-hand thumb rule direction deta hai: thumb current ke along, mudi ungliyan field ke along (Section 12.2.2).
  7. Current loop ke centre par lines lagbhag seedhi hoti hain; n turns wali coil n guna field deti hai (Section 12.2.3).
  8. Solenoid ka field andar uniform aur bahar bar magnet jaisa hota hai; soft iron core ke saath yeh electromagnet ban jaata hai (Section 12.2.4).
  9. Magnetic field mein current-carrying conductor par force lagta hai, jo sabse bada tab hota hai jab current field ke right angles par ho aur zero jab uske along ho (Section 12.3).
  10. Fleming's left-hand rule force deta hai: first finger field, second finger current, thumb force (Section 12.3).
  11. Gharon ko live (red) aur neutral (black) wires se 220 V, 50 Hz AC milta hai; appliances alag 5 A aur 15 A circuits par parallel mein jude hote hain (Section 12.4).
  12. Earth wire (green) metal bodies ko earth potential par rakhti hai; fuse ya MCB overloading ya short circuit mein current kaat deta hai (Section 12.4).
Practice · 16 questions

Practice questions answers ke saath (NCERT “Exercises”)

  1. Quick answerEasyNCERT Exercises Q1

    Ek horizontal card par iron filings chhidki jaati hain, jiske beech se steady current le jaane wali ek lambi vertical wire guzarti hai. Woh kaun sa pattern banati hain?

    Answer dekho

    Answer (B) Wire ke around rings, wire ke paas zyaada ghani

    Seedhi wire ki field lines usko centre maan kar concentric circles hoti hain, jo wire ke paas zyaada paas-paas hoti hain jahan field zyaada strong hai.
  2. Quick answerEasyNCERT Exercises Q2

    Table-lamp ki cord mein live aur neutral wires ke beech ka insulation pighal jaata hai, aur dono wires ek doosre ko chhoo leti hain. Us circuit ke current ka kya hota hai?

    Answer dekho

    Answer (C) Woh bahut badi value tak badh jaata hai

    Yeh short circuit hai: raaste ka resistance lagbhag zero ho jaata hai, isliye current tezi se badhta hai jab tak fuse pighal na jaaye ya MCB trip na ho jaaye.
  3. Quick answerEasyNCERT Exercises Q3

    True ya false?

    1. Current le jaane wali badi circular coil ke centre ke paas field lines lagbhag seedhi aur parallel hoti hain.

      Answer dekho

      Answer Sahi

      Centre par coil ke har hisse ke around bane bade circles ke arcs lagbhag seedhe hote hain, aur sab same taraf point karte hain.

    2. NCERT ke use kiye purane Indian colour code mein green insulation wali wire live wire hoti hai.

      Answer dekho

      Answer Galat

      Green earth wire hai. Live wire red hoti hai aur neutral wire black.
  4. Short answerEasyNCERT Exercises Q4

    Magnetic field banane ke do alag tareeke batao.

    Solution dikhao

    AnswerPermanent magnet se, aur conductor mein electric current se (jaise solenoid ya electromagnet).

    • Ek permanent magnet, jaise bar magnet ya horseshoe magnet.
    • Conductor mein electric current: seedhi wire, coil ya solenoid; soft iron core ke saath, electromagnet.
  5. Short answerMediumNCERT Exercises Q5

    Current le jaane wala ek seedha conductor uniform magnetic field mein rakha jaata hai aur dheere-dheere ghumaya jaata hai. Kis position mein us par force sabse zyaada hota hai, aur kis mein zero?

    Solution dikhao

    AnswerSabse zyaada jab conductor field ke right angles par ho; zero jab woh field ke along ho.

    Force sabse zyaada tab hota hai jab current field lines ke right angles par behta hai. Conductor ko field ki direction ki taraf ghumane par force kam hota jaata hai, aur jab conductor field ke along ho jaata hai to force zero ho jaata hai.

  6. Quick answerHardNCERT Exercises Q6

    Tum laboratory ki saamne wali deewar ki taraf munh karke baithe ho. Protons ka ek beam tumhare saamne vertically upar uthta hai aur ek magnetic field se tumhare left ki taraf mud jaata hai. Field kis taraf point karta hai?

    Solution dikhao

    Protons positive hote hain, isliye current unki motion ki direction mein point karta hai: upar. Force tumhare left ki taraf hai. Fleming's left-hand rule ke liye field dono ke right angles par hona chahiye, isliye woh horizontal hai aur ya to tumhari taraf hai ya tumse door. Second finger upar, thumb left: first finger tumse door point karti hai. To field horizontally saamne wali deewar ki taraf point karta hai.

  7. Short answerMediumNCERT Exercises Q7

    Woh rule ka naam batao aur use state karo jisse tum yeh nikaaloge:

    1. current le jaane wali seedhi wire ke around magnetic field ki direction;

      Solution dikhao

      AnswerRight-hand thumb rule.

      Right-hand thumb rule: wire ko right hand mein aise pakdo ki thumb current ke along ho; tumhari mudi ungliyan field lines ki direction dikhati hain.

    2. magnetic field ke right angles par current le jaane wale seedhe conductor par force ki direction;

      Solution dikhao

      AnswerFleming's left-hand rule.

      Fleming's left-hand rule: left hand ke thumb, first finger aur second finger ko right angles par rakho. First finger field ke along aur second current ke along ho, to thumb force deta hai.

    3. magnetic field mein ghumayi gayi coil mein induce hone wale current ki direction.

      Solution dikhao

      AnswerFleming's right-hand rule.

      Fleming's right-hand rule: right hand ke thumb, first finger aur second finger ko right angles par rakho. First finger field ke along aur thumb conductor ki motion ke along ho, to second finger induced current deti hai.

  8. Short answerEasyNCERT Exercises Q8

    Ghar mein short circuit hone ke do tareeke batao, aur samjhao ki yeh khatarnaak kyun hai.

    Solution dikhao

    AnswerGhisa hua insulation live aur neutral ko chhoone de sakta hai, ya appliance ke andar ka fault unhe jod sakta hai. Current bahut bada ho jaata hai aur wires ko zyaada garam karke aag laga sakta hai.

    Short circuit tab hota hai jab live aur neutral wires seedhe ek doosre ko chhoo leti hain. Aisa wahan ho sakta hai jahan purani ya dabi hui cord ka insulation ghis gaya ho, ya jahan appliance ke andar ka fault unhe jod de. Raaste ka resistance lagbhag zero ho jaata hai, isliye bahut bada current behta hai. Yeh wires ko bahut garam kar deta hai aur insulation pighla sakta hai, appliances kharab kar sakta hai aur aag laga sakta hai, jab tak fuse ya MCB supply na kaat de.

  9. Short answerMediumNCERT Exercises Q9

    Samjhao ki metal body wale electric toaster ko use karne wale insaan ko earth wire kaise bachati hai. Aise appliances ko earth karna kyun zaroori hai?

    Solution dikhao

    AnswerAgar live wire body ko chhoo le, to fault current low-resistance earth wire se behta hai. Body earth potential par rehti hai aur fuse ud jaata hai, isliye insaan ko shock nahi lagta.

    Earth wire toaster ki metal body ko zameen mein gaade plate se jodti hai. Agar fault ki wajah se live wire body ko chhoo le, to current is low-resistance raaste se earth mein behta hai. Yeh toaster chhoone wale insaan se nahi guzarta. Body earth ke potential par rehti hai, aur bada current aam taur par fuse pighla kar supply kaat deta hai.

    Earthing ke bina metal body bina kisi khatre ke sign ke 220 V par ho sakti thi, aur use chhoone wale pehle insaan ko zor ka shock lagta.

  10. NumericalMedium

    Ek electric kettle ki rating 1210 W, 220 V hai.

    1. Woh kitna current leti hai, nikaalo.

      A
      Solution dikhao

      I=P/V=1210/220=5.5 A.

    2. Kya use 5 A circuit ke socket mein lagana chahiye ya 15 A circuit ke? Samjhao.

      Solution dikhao

      Answer15 A circuit, kyunki 5.5 A, 5 A se zyaada hai.

      5.5 A lighting circuit ki 5 A rating se zyaada hai, isliye yeh use overload kar dega. Kettle ko 15 A power circuit par use karna chahiye.

  11. Quick answerMedium

    Assertion (A): Lambe current-carrying solenoid ke andar magnetic field uniform hota hai. Reason (R): Lambe solenoid ke andar field lines seedhi, parallel aur barabar doori par hoti hain.

    Answer dekho

    Answer (A) A aur R dono true hain, aur R, A ka sahi explanation hai

    Dono statements true hain, aur seedhi, parallel, barabar doori wali lines ka pattern hi uniform field ka matlab hai, isliye R, A ko explain karta hai.
  12. Quick answerMedium

    Assertion (A): Magnetic field ke parallel chalne wale electron par koi magnetic force nahi lagta. Reason (R): Chalte charge par magnetic force sabse zyaada tab hota hai jab woh field lines ke along chalta hai.

    Answer dekho

    Answer (C) A true hai, lekin R false hai

    A true hai: field ke along motion par koi force nahi. R false hai: force field ke right angles par motion ke liye sabse zyaada hota hai, aur uske along zero.
  13. Long answerHard

    Padho aur jawab do. Meera ke flat mein lights aur fans ke liye ek 5 A circuit hai aur kitchen aur bathroom ke liye ek 15 A circuit, dono 220 V par. Ek shaam uski family 15 A circuit par ek saath 2 kW ka geyser, 1 kW ka induction cooktop aur 750 W ka mixer-grinder chalati hai.

    1. 15 A circuit mein total current nikaalo.

      A
      Solution dikhao

      Total power =2000+1000+750=3750 W hai. Current I=3750/220≈17 A hai.

    2. Kya hoga, aur kyun?

      Solution dikhao

      AnswerCircuit overloaded hai (17 A > 15 A), isliye fuse pighal jaata hai ya MCB trip ho jaata hai.

      Lagbhag 17 A, 15 A rating se zyaada hai. Circuit overloaded hai, isliye fuse pighal jaata hai (ya MCB trip ho jaata hai) aur teeno appliances band ho jaate hain. Isse wiring zyaada garam hone se bachti hai.

    3. Geyser ka earth connection hona kyun zaroori hai?

      Solution dikhao

      AnswerIski metal body hai aur yeh paani ke paas use hota hai; earthing kisi bhi leakage current ko insaan se guzarne ke bajaay zameen mein bhej deti hai.

      Geyser ki metal body hai aur yeh geele bathroom mein use hota hai. Agar uski live wire body ko chhoo le, to earth wire current ko safely zameen tak le jaati aur fuse uda deti. Current kisi insaan se nahi guzarta.

    4. Family ki aadaton mein ek badlaav suggest karo.

      Solution dikhao

      AnswerGeyser, cooktop aur mixer ek saath mat chalao; khaana banate waqt geyser band kar do.

      Heavy appliances ek ke baad ek use karo: jaise, jab cooktop aur mixer chal rahe hon tab geyser band kar do. Tab current 15 A se kam rehta hai.

  14. DiagramMedium

    Aise solenoid ki field lines banao jismein uske left end se dekhne par current clockwise behta hai. Uske north aur south ends mark karo aur andar ka field dikhao.

    Solution dikhao

    AnswerLeft end S hai aur right end N. Andar seedhi parallel lines left se right point karti hain; bahar lines right end se ghoom kar wapas left end tak jaati hain.

    1. Left end se dekhne par clockwise current us end ko south pole bana deta hai, isliye right end north pole hai.
    2. Andar seedhi, parallel, barabar doori wali lines banao jinke arrows left (S) se right (N) point karein.
    3. Bahar aisi lines banao jo right end se niklein, coil ke upar aur neeche ghoomein, aur left end mein ghusein, bilkul bar magnet ke field ki tarah.
  15. Quick answerEasy

    Inhe us order mein lagao jismein mains supply street se ceiling fan tak inse guzarti hai.

    1. Main switch
    2. Fuse box
    3. Electricity meter
    4. Board fuse
    5. Fan ka switch
    Answer dekho
    Answer
    1. Board fuse
    2. Electricity meter
    3. Main switch
    4. Fuse box
    5. Fan ka switch
    Supply electricity board ke fuse, meter aur main switch se guzarti hai, phir har circuit ko supply dene wale fuse box se, aur aakhir mein fan ke switch se.
  16. Quick answerEasy

    Electromagnet ka core iron ka hota hai, kyunki yeh current off hote hi apna magnetism kho deta hai.

    Answer dekho

    Answer soft

    Soft iron aasaani se magnetise ho jaata hai aur current rukne par apna magnetism kho deta hai, isliye electromagnet ko on aur off kiya ja sakta hai.

Apna NCERT exercise question dhoondo

Hamare practice questions ncert.ai ke liye likhe gaye hain aur NCERT exercises ko follow karte hain. Apni textbook ke question se match karne wala question dhoondo; uska answer uske saath hai.

Tumhari NCERT textbook meinYahan practice question
NCERT in-text Questions p. 196, Q1Practice 12.1 (NCERT in-text questions, pp. 196 aur 200) · Q1
NCERT in-text Questions p. 200, Q1Practice 12.1 (NCERT in-text questions, pp. 196 aur 200) · Q2
NCERT in-text Questions p. 200, Q2Practice 12.1 (NCERT in-text questions, pp. 196 aur 200) · Q3
NCERT in-text Questions p. 200, Q3Practice 12.1 (NCERT in-text questions, pp. 196 aur 200) · Q4
NCERT in-text Questions p. 201, Q1Practice 12.2 (NCERT in-text questions, pp. 201–202) · Q1
NCERT in-text Questions p. 201, Q2Practice 12.2 (NCERT in-text questions, pp. 201–202) · Q2
NCERT in-text Questions p. 202, Q3Practice 12.2 (NCERT in-text questions, pp. 201–202) · Q3
NCERT in-text Questions p. 203, Q1Practice 12.3 (NCERT in-text questions, pp. 203–204) · Q1
NCERT in-text Questions p. 204, Q2Practice 12.3 (NCERT in-text questions, pp. 203–204) · Q2
NCERT in-text Questions p. 204, Q3Practice 12.3 (NCERT in-text questions, pp. 203–204) · Q3
NCERT in-text Questions p. 205, Q1Practice 12.4 (NCERT in-text questions, p. 205) · Q1
NCERT in-text Questions p. 205, Q2Practice 12.4 (NCERT in-text questions, p. 205) · Q2
NCERT in-text Questions p. 205, Q3Practice 12.4 (NCERT in-text questions, p. 205) · Q3
NCERT Exercises Q1Exercises · Q1
NCERT Exercises Q2Exercises · Q2
NCERT Exercises Q3Exercises · Q3
NCERT Exercises Q4Exercises · Q4
NCERT Exercises Q5Exercises · Q5
NCERT Exercises Q6Exercises · Q6
NCERT Exercises Q7Exercises · Q7
NCERT Exercises Q8Exercises · Q8
NCERT Exercises Q9Exercises · Q9

Quick check: MCQs

  1. 12.1 Magnetic Field aur Field Lines4 questions
  2. 12.2.2 Right-Hand Thumb Rule4 questions
  3. 12.2.4 Solenoid mein Current ke kaaran Magnetic Field4 questions
  4. 12.3 Magnetic Field mein Current-Carrying Conductor par Force4 questions
  5. 12.4 Domestic Electric Circuits4 questions
Glossary · 14

Key terms (English + Hindi)

compass needleदिक्सूचक सुईdiksoochak sui
Ek chhota, halka magnet jo pivot par aise laga ho ki free hokar ghoom sake; uska north pole lagbhag geographic north ki taraf point karta hai.Chapter mein pehli baar yahan aaya →
earth wireभूसंपर्क तारbhoosampark taar
Ek green safety wire jo appliance ki metal body ko zameen mein gaade gaye metal plate se jodti hai.Chapter mein pehli baar yahan aaya →
electromagnetविद्युत चुंबकvidyut chumbak
Insulated wire ki coil ke andar soft iron core, jo sirf tab tak magnet rehta hai jab tak coil mein current behta hai.Chapter mein pehli baar yahan aaya →
Fleming's left-hand ruleफ्लेमिंग का वामहस्त नियमFleming ka vaamhast niyam
Left hand ke thumb aur pehli do ungliyon ko right angles par rakho: first finger field ke along, second finger current ke along; thumb force deta hai.
fuseविद्युत फ्यूज़vidyut fuse
Live wire ke saath series mein low melting point wali ek chhoti wire; current bahut bada hone par yeh pighal kar circuit tod deti hai.Chapter mein pehli baar yahan aaya →
live wireविद्युन्मय तारvidyunmay taar
High potential wali mains wire (neutral ke relative 220 V); purane Indian colour code mein red.Chapter mein pehli baar yahan aaya →
magnetic fieldचुंबकीय क्षेत्रchumbakiya kshetra
Magnet ya current ke around ka woh region jismein magnetic force detect kiya ja sakta hai. Iski strength aur direction dono hoti hain.
magnetic field lineचुंबकीय क्षेत्र रेखाchumbakiya kshetra rekha
Woh line jiske along ek chhoti compass needle point karegi; iska arrow dikhata hai ki north pole kidhar point karta hai.Chapter mein pehli baar yahan aaya →
neutral wireउदासीन तारudaaseen taar
Mains supply ki return wire, jo earth ke potential ke kareeb rakhi jaati hai; purane colour code mein black.Chapter mein pehli baar yahan aaya →
overloadingअतिभारणatibhaaran
Circuit se uski design se zyaada current lena, jaise us par bahut saare appliances chala kar.Chapter mein pehli baar yahan aaya →
right-hand thumb ruleदक्षिण-हस्त अंगुष्ठ नियमdakshin-hast angushth niyam
Current-carrying wire ko right hand mein aise pakdo ki thumb current ke along ho; mudi ungliyan field lines ki direction dikhati hain.
short circuitलघुपथनlaghupathan
Aisa fault jismein live aur neutral wires seedhe chhoo leti hain, isliye resistance lagbhag zero ho jaata hai aur current bahut bada ho jaata hai.Chapter mein pehli baar yahan aaya →
solenoidपरिनालिकाparinalika
Insulated wire ki ek lambi, kas kar lapeti coil jismein kai turns hon, aur jiski shape tube jaisi ho.Chapter mein pehli baar yahan aaya →
uniform magnetic fieldएकसमान चुंबकीय क्षेत्रeksamaan chumbakiya kshetra
Aisa field jiski kisi region mein har jagah strength aur direction same ho, jise seedhi, parallel, barabar doori wali lines se banaya jaata hai.Chapter mein pehli baar yahan aaya →

Tum chapter ke end tak pahunch gaye