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CHAPTER 11

Electricity

Overview

Switch on karte hi bulb jal uthta — par andar kya hota hai? Is chapter mein charge ka flow (current), voltage, resistance, Ohm's law, series-parallel circuits aur heating effect padhenge. Electricity ke numericals board mein pakke aate hain — unit conversions (mA→A, mm²→m²) sabse common galti hai, inpe pakad banao.

Key Concepts

  • 01Electric current: charge ka flow. I = Q/t; SI unit ampere (A). Ek ampere = 1 coulomb/second.
  • 02Potential difference: do points ke beech per-unit-charge kaam — V = W/Q; unit volt (V).
  • 03Ohm's law: constant temperature par V ∝ I, yaani V = IR.
  • 04Resistance current ka opposition hai; R = ρl/A — wire lambi aur patli hogi to resistance zyada.
  • 05Series circuit: current same rehta hai, resistances add hote hain. Parallel: voltage same rehta hai, equivalent resistance girta hai.
  • 06Joule's law of heating: H = I²Rt — heater, electric iron, fuse aur bulb filament isi principle par chalte hain.

Important Formulas

Current: I = Q/t
Ohm's law: V = IR
Resistance: R = ρl/A
Series: Rs = R₁ + R₂ + R₃ + ...
Parallel: 1/Rp = 1/R₁ + 1/R₂ + 1/R₃ + ...
Heat: H = I²Rt
Power: P = VI = I²R = V²/R
1 kWh = 3.6 × 10⁶ J

Practice Questions

  1. 01Ek resistor par 12 V lagane par 3 A current aata hai — resistance nikalo.
  2. 02Do resistors 4 Ω aur 6 Ω — pehle series mein, phir parallel mein. Dono cases mein equivalent resistance nikalo.
  3. 03Ek 100 W ka bulb 220 V par — filament ka resistance kitna hai?
  4. 04Ek heater 5 A current ko 220 V par 2 ghante chala — kharch hui energy kWh mein nikalo.
  5. 05Charge 5 A current se 1 minute tak behta hai — kitna coulomb charge gaya?
Summary

Current charge ka flow hai (I = Q/t), potential difference kaaran hai (V = W/Q). Ohm's law V = IR unhe jodta hai. Series mein resistance badhta hai, parallel mein ghatta hai. Circuit mein electric energy heat mein badalti hai — H = I²Rt. Power P = VI. Bijli ka bill kWh mein — 1 unit = 1 kWh = 3.6 × 10⁶ J.

Handwritten notes
Handwritten — class notes
Handwritten — class notes
Diagrams + workings
Diagrams + workings

Chapter-end quiz

5 MCQs

Option tap karo — turant pata chalega sahi ya galat, explanation ke saath.

  1. Q1.Resistance ka SI unit kya hai?

  2. Q2.Ohm's law ka formula kya hai?

  3. Q3.Resistors ko parallel mein jodne par equivalent resistance kaisa hota hai?

  4. Q4.Joule's law of heating ka formula kya hai?

  5. Q5.1 kilowatt-hour (kWh) barabar hai?

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