Class 7 Science · Chapter 3
Short answer:
Class 7 Science Curiosity Chapter 3 — "Electricity: Circuits and their Components" — sikhata hai ki cell, bulb, switch aur connecting wires se ek simple electric circuit kaise banta hai, current kaise flow karta hai, aur series-parallel circuits me kya farak hota hai. Yeh chapter conductors-insulators aur circuit diagrams padhna-banana bhi cover karta hai — poori tarah practical aur hands-on approach ke sath.
Chapter 3 poore Class 7 Science Curiosity book ka sabse hands-on aur practical chapter hai — yahan bachche apna khud ka simple electric circuit banana seekhte hain, cell se lekar bulb tak, switch ke through control karte hue. Yeh chapter sirf theory nahi hai, balki real-life electricity ke basic working principles ko samajhne ki neev hai — jo aage Class 8, 9, 10 ke Physics chapters (Current Electricity, Electromagnetism) me kaam aati hai.
Is topic ko samajhna zaroori hai kyunki roz ke ghar-office me jo bhi electrical devices chalte hain — bulb, fan, charger — sab ek closed circuit ke basic principle par hi kaam karte hain. NCERT ka approach yahan conceptual clarity par hai: components ke symbols, unka function, aur circuit diagram padhna-banana — exam ke liye bhi aur real understanding ke liye bhi equally important hai.
Chapter 3 Summary — 5 Minute Revision
Class 7 Science Curiosity Chapter 3, "Electricity: Circuits and their Components," students ko electric circuit ke basic building blocks se parichay karata hai — cell/battery (energy source), bulb (light output), switch (on/off control), aur connecting wires (conductor path). Chapter yeh sikhata hai ki closed circuit me hi current flow hota hai, open circuit me nahi. Series arrangement me current ka single path hota hai (dim glow), jabki parallel arrangement me multiple independent paths hote hain (bright glow). Conductors (copper) easily current flow hone dete hain, insulators (rubber, plastic) nahi. Standard circuit symbols padhna aur diagram banana is chapter ka core practical skill hai, jo aage ke Physics chapters ki neev banata hai.
Yeh chapter current 2026-27 rationalised "Curiosity" 12-chapter syllabus ka part hai — purani 13-chapter book ke "Electric Current and its Effects" (heating/magnetic effects) jaise topics is chapter me exclude hain, unhe confuse na karein.
In-Text Questions — Solutions
Ek electric cell circuit me kya kaam karta hai?
Electric cell circuit ko electrical energy ka source deta hai. Uske andar stored chemical energy chemical reaction ke through electrical energy me convert hoti hai, jo cell ke do terminals (positive aur negative) ke beech ek potential difference banati hai. Yahi potential difference circuit me connected components (jaise bulb) ke through current ko drive karta hai, jab tak circuit closed (complete) ho.
Switch circuit me kyun zaroori hai?
Switch circuit ko on ya off control karne ke liye zaroori hai. Jab switch close (band/complete) hota hai, circuit complete ho jaata hai aur current flow hone lagta hai — bulb jalta hai. Jab switch open (khula/incomplete) hota hai, circuit break ho jaata hai, current flow rukta hai aur bulb bujh jaata hai. Bina switch ke har baar circuit connect/disconnect karne ke liye wires khud se jodna-todna padega, jo practical nahi hai.
Do bulbs ko series me lagane par unki brightness kaisi hoti hai aur kyun?
Series me lagaye do bulbs dim glow karte hain, single parallel bulb ke comparison me. Iski wajah hai ki series arrangement me current ka sirf ek hi path hota hai — dono bulbs ka combined resistance total circuit resistance badha deta hai, jisse current ki magnitude kam ho jaati hai. Kam current ka matlab hai kam power dissipation har bulb me, isliye roshni dim hoti hai.
Conductor aur insulator ka circuit banane me kya role hai?
Conductors (jaise copper wire) current ko easily flow karne dete hain, isliye inhe connecting wires ke roop me circuit ke components jodne ke liye use karte hain. Insulators (jaise plastic ya rubber coating wires ke upar) current ko flow nahi hone dete, isliye inka use safety ke liye hota hai — taaki current sirf intended path se guzre aur accidental short-circuit ya shock na ho. Dono ka sahi combination hi ek safe aur working circuit banata hai.
Exercise Questions — Solutions (Q1–Q6)
1. Fill in the blanks: (a) Circuit ka woh part jo electricity ko flow hone se roke bina apni resistance ke through jaane deta hai, use _______ kehte hain. (b) Ek switch circuit ko _______ ya _______ karta hai.
(a) conductor. (b) open (band karna / circuit toड़ना), close (complete karna / circuit jodna).
2. State whether True or False: A cell ke andar chemical energy directly light energy me convert hoti hai jab woh bulb se judi hoti hai.
False. Cell ke andar chemical energy pehle electrical energy me convert hoti hai (cell terminals ke through), aur woh electrical energy circuit se hoti hui bulb tak pahunchti hai jahan wo light energy (aur heat) me convert hoti hai. Energy conversion do steps me hota hai, direct nahi.
3. Trace the path of current in the circuit shown in your textbook figure (a simple circuit with cell, switch and bulb) and mark the direction of conventional current flow.
Conventional current battery ke positive terminal se nikalta hai, connecting wire ke through switch tak jaata hai, switch band hone par (closed position) aage bulb ke andar filament se hokar guzarta hai, aur wapas connecting wire ke zariye battery ke negative terminal par lautta hai. Path: +ve terminal → wire → switch → bulb → wire → −ve terminal (poora loop, kisi bhi jagah break nahi hona chahiye).
4. Two bulbs are connected to a battery. In one arrangement they glow dimly and in another they glow bright. Explain which arrangement is series and which is parallel, giving reasons.
Jo arrangement me bulbs dimly glow karte hain woh series connection hai — kyunki series me current ka ek hi single path hota hai, dono bulbs se guzarne me total resistance badh jaati hai isliye current kam ho jaata hai aur roshni dim hoti hai. Jo arrangement me bulbs bright glow karte hain woh parallel connection hai — kyunki parallel me har bulb ko battery se apna alag independent path milta hai, poora battery voltage har bulb ko milta hai isliye current zyada aur roshni bright hoti hai.
5. Why should you never test whether a circuit is working by touching the two terminals of a cell with your tongue or fingers?
Yeh khatarnak practice hai kyunki: (i) Agar voltage zyada ho (jaise kai cells series me joड़e ho) to body ke through current flow karke electric shock lag sakta hai. (ii) Cell terminals par chemicals lage ho sakte hain jo skin ya tongue ko chemical burn de sakte hain. (iii) Yeh unsafe scientific practice hai — hamesha bulb, LED, ya proper tester (jaise electric circuit tester) se hi circuit test karna chahiye, kabhi bhi apne body ko conductor ki tarah use nahi karna chahiye.
6. A torch uses two cells of 1.5 V each. If the cells are connected correctly (positive to negative in series), what will be the total voltage available to the bulb? Also draw the circuit diagram using correct symbols.
Jab do cells series me correctly (ek cell ka positive terminal doosre ke negative se) joड़e jaate hain, unki voltages add ho jaati hain.
Total voltage = 1.5 V + 1.5 V = 3.0 V
Circuit diagram: do battery symbols (long line + short line ek series me) → connecting wires → bulb symbol (circle ke andar cross/X) → switch symbol (do dots ke beech ek titled line) → wapas battery tak, poora ek closed loop banate hue. Standard NCERT symbols use karein: seedhi line ke sath (long-short-long-short) cell, circle-cross bulb, aur diagonal line switch ke liye.
Important Equations — Ek Nazar Me
| Concept | Rule / Relation | Note |
|---|---|---|
| Series voltage (cells) | V_total = V1 + V2 + ... | Same polarity order me jode gaye cells ki voltage add hoti hai |
| Series circuit — current path | Single path — ek hi current sab components se guzarta hai | Ek component fail → poora circuit off |
| Parallel circuit — current path | Multiple independent paths — har branch ko full voltage milta hai | Ek component fail → baaki chalte rehte hain |
| Conductor | Material jisme se electricity easily flow kare (e.g. copper, aluminium) | Low resistance |
| Insulator | Material jisme se electricity flow nahi kare (e.g. rubber, plastic, wood) | High resistance, current block karta hai |
| Closed circuit | Complete unbroken loop — current flow hota hai, bulb jalta hai | Switch ON position |
| Open circuit | Broken/incomplete loop — current flow nahi hota, bulb nahi jalta | Switch OFF position |
↔ Table ko side me swipe karein
Common Mistakes — Yahan Marks Kat te Hain
- Circuit diagram me switch ko galat jagah ya galat symbol se dikhana — hamesha standard NCERT symbol (diagonal tilt line) use karein, apna symbol invent na karein.
- Cell aur battery ko same samajhna — cell ek single unit hai, battery do ya zyada cells ka combination hai (series me joड़i hui).
- Conventional current ki direction confuse karna — current hamesha battery ke positive terminal se nikal kar circuit se hoti hui negative terminal par wapas jaata hai maana jaata hai (electron flow iske opposite hota hai, par exam me conventional current hi likhein jab tak specifically electron flow na poocha jaaye).
- Open circuit aur short circuit ko same maan lena — open circuit me path incomplete hota hai (current flow hi nahi hota), jabki short circuit me current bina resistance ke direct path le leta hai jo dangerous hota hai — dono alag concepts hain.
- Series aur parallel circuit ke brightness effect ko galat explain karna — yaad rakhein series me resistance add hoti hai (dim glow), parallel me har branch ko independent full voltage milta hai (bright glow).
- 'Electric Current and its Effects' (heating/magnetic effects, electromagnet) ke topics ko is chapter ka part samajh lena — yeh purani 13-chapter book ka alag chapter tha jo current 2026-27 Curiosity syllabus me rationalise ho chuka hai; is chapter me sirf basic circuit-building tak scope limited hai.
Board-Style Important Questions
- Draw a labelled circuit diagram showing a cell, a switch, and a bulb connected in a closed loop, using standard symbols.
- Differentiate between an open circuit and a closed circuit with the help of a simple diagram.
- Two identical bulbs are connected first in series and then in parallel with the same battery. Compare their brightness in both cases with reasons.
- List any three conductors and three insulators used commonly in household electric circuits, and explain why insulators are necessary for safety.
- Explain, with reasons, why we should never touch the terminals of a cell with wet hands or tongue while testing a circuit.
- State the function of a switch in an electric circuit and explain what happens to the bulb when the switch is (a) open (b) closed.
Aksar Poochhe Jaane Wale Sawaal
Class 7 Science Chapter 3 'Electricity: Circuits and their Components' me kya kya topics cover hote hain?
Is chapter me electric cell, battery, bulb, switch, connecting wires jaise basic circuit components, unke symbols, simple electric circuit banana, current ka flow, conductors aur insulators, aur series-parallel circuits ka basic introduction cover hota hai. Curiosity book (2026-27 rationalised syllabus) me yeh chapter practical hands-on circuit-making activities par zyada focus karta hai.
Class 7 me series aur parallel circuit ka difference kya hai?
Series circuit me current ka sirf ek hi path hota hai — sab components ek line me jude hote hain, agar ek component fail ho jaaye to poora circuit break ho jaata hai. Parallel circuit me multiple paths hote hain — har component ko apna independent connection milta hai, ek component fail hone par baaki components chalte rehte hain. Bulbs series me dim aur parallel me bright glow karte hain.
Kya is chapter me 'Electric Current and its Effects' wale heating/magnetic effects bhi aate hain?
Nahi. 'Electric Current and its Effects' (jisme heating effect, magnetic effect, electromagnet jaise topics the) purani 13-chapter NCERT book ka alag chapter tha jo 2026-27 rationalised Curiosity syllabus me exclude ho chuka hai. Current Chapter 3 sirf basic circuits, components aur unke connections tak limited hai — heating/magnetic effects is chapter ka part nahi hain.
Class 7 Science Curiosity book 2026-27 syllabus me kitne chapters hain?
Curiosity book (current rationalised 2026-27 edition) me total 12 chapters hain, jo purani 13-chapter structure se reduce kiye gaye hain. Kai topics jaise Nutrition in Plants/Animals, Acids-Bases-Salts (separate chapter), Respiration, Motion and Time, Electric Current and its Effects, Forests, Wastewater Story ko rationalise kar diya gaya hai — inhe purani book se confuse na karein.
Circuit diagram banate waqt kaunse symbols use karne chahiye?
NCERT standard symbols follow karne chahiye: cell — do parallel lines (ek badi/long line positive, ek choti/short line negative), battery — multiple cells ka combination symbol, bulb — circle ke andar cross (X), switch — ek diagonal line jo do connection points ke beech tilt hoti hai (open/closed dikhane ke liye), connecting wire — seedhi solid line. Exam me hamesha inhi standard symbols ka use karein, apne khud ke symbols na banayein.
Chapter 3 ke exercise questions solve karte waqt kaunsi common mistakes avoid karni chahiye?
Sabse common mistakes: circuit diagram me switch ko galat jagah dikhana, positive-negative terminal confuse karna, 'current flow' aur 'electron flow' ki direction mix up karna, aur series/parallel arrangement ke practical effects (brightness) ko galat explain karna. In sab mistakes ka detailed breakdown neeche 'Common Mistakes' section me diya gaya hai — exam se pehle zaroor revise karein.
Class 7 Science — Saare Chapters
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