Class 7 Science Chapter 3: Electricity: Circuits and their Components (Hinglish Notes)
Ye chapter 5 lines mein
Electricity: Circuits and their Components samjhaata hai ki torch kaise kaam karti hai. Electric cell ka ek positive aur ek negative terminal hota hai, aur cells ko positive se negative jodne pe battery banti hai. Lamp ya LED tabhi jalta hai jab wo ek poore raaste, yaani electric circuit, ka hissa ho, jise switch kholta ya band karta hai. Circuit symbols se banaaye jaate hain, aur unhe copper jaise conductors chahiye jin pe plastic jaise insulators ka cover ho.
Ye chapter kis baare mein hai?
Bhakra Nangal Dam ke hydroelectric power house ki school trip se pehle Nihal aur uske saathi bijli ke upyogon ki list banaate hain, aur list badhti hi jaati hai: khaana banaana, roshni, yaatayaat, garam aur thanda karna, manoranjan, sanchaar aur bhi bahut kuch. Bijli power stations se taaron ke zariye gharon tak aati hai, par wo supply khatarnaak hai. Isliye chapter bijli ko ek surakshit, saath le jaane laayak srot, electric cell, se samajhta hai, aur shuruaat ek aam device se karta hai: torch.
Cells aur batteries
Torch mein do ya zyaada electric cells hote hain. Har cell ke do terminal hain: chhoti dhaatu ki topi positive (+) terminal hai aur chapti dhaatu ki plate negative (−) terminal. Torch mein cells ek khaas kram mein rakhe jaate hain, jahan ek cell ka positive terminal agle ke negative terminal ko chhoota hai. Aise jude cells battery banaate hain, jo zyaada der tak aur/ya zyaada energy deti hai. Mobile phone ke akele cell ko bhi battery kehte hain. Aur padho cell, battery aur lamp mein.
Lamps: incandescent aur LED
Purani torches mein incandescent lamp hota hai. Iske kaanch ke bulb mein ek patla taar, filament, do mote taaron pe tika hota hai; ek mota taar base ke dhaatu ke case se aur doosra dhaatu ki nok se juda hai, aur yahi lamp ke do terminal hain. Current filament ko itna garam karta hai ki wo chamakne lagta hai. Aaj zyaadatar torches mein LED, yaani light emitting diode, hota hai, jisme filament nahi hota. LED ka lamba taar positive aur chhota taar negative terminal hai, aur current isme sirf ek disha mein jaata hai.
Lamp jalaana: electric circuit
Cell aur lamp ko chhe tareekon se jodne pe pata chalta hai ki lamp tabhi jalta hai jab lamp ka ek terminal cell ke ek terminal se aur doosra terminal cell ke doosre terminal se jude. Isse electric circuit banta hai, electric current ke liye ek poora raasta. Current cell ke positive terminal se, circuit se hokar, negative terminal ki taraf behta maana jaata hai. Incandescent lamp kisi bhi taraf jodne pe jalta hai, par LED tabhi jalta hai jab uska lamba taar positive taraf jude. Toote filament waale lamp ko fused kehte hain: toot current ko rok deti hai. Padho electric circuit kaise banta hai.
Switches
Do drawing pins, ek safety pin aur cardboard ke tukde se saral switch ban jaata hai. Jab safety pin dono drawing pins ko chhooti hai, gap band ho jaata hai: switch ON hai aur circuit closed, isliye current behta hai aur lamp jalta hai. Jab nahi chhooti, gap current ko rok deta hai: switch OFF hai aur circuit open. Switch circuit mein kahin bhi lagaaya ja sakta hai, aur ghar ke switch bhi isi tarah kaam karte hain.
Circuit diagrams
Har baar asli cells aur taar banaana dheema hai, isliye hum symbols use karte hain: cell ke liye do asamaan lambi lines (lambi line positive), lamp ke liye cross waala gola, LED ke liye bar aur do teeron waala triangle, aur switch aur taar ke liye saral nishaan. In symbols se bana circuit ka chitra circuit diagram hai. International Electrotechnical Commission jaisi sansthaayein maanak symbols tay karti hain, taaki har jagah log diagram ek hi tarah padhein.
Conductors aur insulators
Cell aur lamp se bana tester, jiske do taar khule chhode gaye hon, batata hai ki kaunse padaarth current guzaarte hain. Chaabi, sikke, pin aur aluminium foil lamp jalaate hain: ye conductors hain, aur sab dhaatuyein hain. Lakdi, plastic, kaanch, kaagaz, mom aur rubber nahi jalaate: ye insulators hain. Silver, copper aur gold baaki dhaatuon se behtar current chalaate hain, aur taar copper ke bante hain kyunki wo sasta aur bhar-poor hai. Plastic, rubber aur ceramics jaise insulators taar, plug ke top aur switch dhakkar hamari raksha karte hain. Hamara shareer conductor hai, isliye geele haathon se switch ya plug mat chhuo, geeli jagah bijli ke device mat chalaao aur kharaab taar mat chhuo. Cells chhote devices ke liye direct current (DC) dete hain, jabki deewaar ka socket power plant se aaya alternating current (AC) bade appliances ke liye deta hai. Padho conductors aur insulators.
Har activity, Table 3.1 aur 3.3, Let Us Enhance Our Learning ke sawaal aur projects ke jawab Chapter 3 ke NCERT solutions mein hain.
Key terms (zaroori shabd)
| Term | Matlab |
|---|---|
| Electric cell | Bijli ka chhota, saath le jaane laayak srot jiske do terminal hain: positive (+) dhaatu ki topi aur negative (−) chapti dhaatu ki plate. |
| Battery | Do ya zyaada cells jo is tarah jude hon ki ek ka positive terminal agle ke negative terminal se mile. |
| Filament | Incandescent lamp ke andar ka patla taar jo current guzarne pe garam hokar chamakta hai. |
| LED (light emitting diode) | Bina filament ka lamp. Iska lamba taar positive aur chhota taar negative terminal hai, aur current isme sirf ek disha mein jaata hai. |
| Electric circuit | Poora raasta jisme current behta hai: cell ke positive terminal se, components se hokar, waapas negative terminal tak. |
| Switch | Saral device jo circuit ko poora (ON, closed circuit) ya tod (OFF, open circuit) deta hai. Ise circuit mein kahin bhi lagaa sakte hain. |
| Circuit diagram | Electric circuit ka chitra jo components ke maanak (standard) symbols se banaaya jaata hai. |
| Conductor | Aisa padaarth jisme se current aasaani se behta hai, jaise copper aur aluminium jaisi dhaatuyein. |
| Insulator | Aisa padaarth jisme se current nahi guzarta, jaise plastic, rubber, kaanch, lakdi aur ceramics. Inhe poor conductors bhi kehte hain. |
Is chapter ke topics
Practice karo
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Electric cell ka positive terminal kaunsa hissa hai?
Jawab dekho
Jawab: (b) Dhaatu ki topi
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Battery banaane ke liye cells kaise jodte hain?
Jawab dekho
Jawab: (c) Ek ka positive agle ke negative se
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LED ka kaunsa taar positive terminal hai?
Jawab dekho
Jawab: (b) Lamba taar
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Switch OFF ho to circuit:
Jawab dekho
Jawab: (b) Khula (open) hai
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Inme se insulator kaunsa hai?
Jawab dekho
Jawab: (c) Rubber ka eraser
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Cell ke symbol mein lambi line kya dikhati hai?
Jawab dekho
Jawab: (b) Positive terminal
Students ke sawal
Class 7 Science Chapter 3 ke mukhya topics kya hain?
Bijli ke upyog aur suraksha; torch ek saral circuit ke roop mein; electric cells, batteries, incandescent lamps aur LEDs; poore circuit mein lamp jalaana; switches; maanak symbols waale circuit diagrams; aur conductors aur insulators, DC aur AC ki chhoti si baat ke saath.
Kya Electricity: Circuits and their Components nayi Curiosity kitaab mein hai?
Haan. Ye Curiosity, Class 7 Science ki kitaab (Reprint 2026-27) ka Chapter 3 hai, pages 23 se 40 tak. Ye Nihal ki class se shuru hota hai, jo Bhakra Nangal Dam ki trip se pehle bijli ke upyogon ki list banaati hai.
Lamp sirf poore circuit mein hi kyun jalta hai?
Current ko cell ke ek terminal se nikalkar, lamp se hokar, doosre terminal mein waapas aana hota hai. Agar kahin gap ho, ya lamp ke dono taar ek hi terminal pe jude hon, to poora raasta nahi banta, current nahi behta, aur filament garam hokar nahi chamakta.
Bijli ke taar copper ke kyun bante hain aur unpe plastic kyun hota hai?
Copper ek dhaatu hai, isliye usme current aasaani se behta hai, aur ye silver ya gold se sasta aur zyaada milta hai, jo isse bhi achha current chalaate hain. Plastic ya rubber ka cover insulator hai: ye current ko hamare shareer mein jaane se rokta hai aur bijli ke jhatke se bachaata hai.
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