Electricity Practice
Solve chapter-level practice questions for Electricity with reveal-only solutions and quick revision support.
Practice Set 1 — Current, Potential Difference, and Ohm's Law
Definitions, statement of Ohm's law, and basic formula calculations.
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Practice Set 2 — Resistance and Resistivity
Factors affecting resistance, resistivity formula, and material properties.
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Practice Set 3 — Series and Parallel Resistors
Equivalent resistance calculations and circuit analysis.
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Practice Set 4 — Heating Effect and Joule's Law
Heat generated in conductors and practical heating applications.
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Practice Set 5 — Electric Power and Electricity Bill
Power calculations and commercial energy unit problems.
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Practice Set 6 — Mixed Higher-Order Problems
Comprehensive circuit analysis and application questions.
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Quick Q&A Before You Revise
Why are household appliances connected in parallel and not in series?
In parallel: (1) Each appliance gets the full supply voltage (230 V in India), so it operates at its rated power. (2) Each appliance can be switched on/off independently. (3) If one appliance fails, others continue to work. In series, voltage divides, appliances would not work at rated power, and failure of one breaks the whole circuit.
What is the difference between electrical energy and electric power?
Electric power is the rate of doing work or converting energy: P = energy/time (unit: watt). Electrical energy is the total work done or energy converted in a given time: E = P × t (unit: joule or kWh). Power tells how fast; energy tells how much total.
Why is a thick copper wire better than a thin copper wire for carrying high current?
A thicker wire has a larger cross-sectional area, giving lower resistance (R = ρl/A). Lower resistance means less energy is wasted as heat (H = I²Rt), and the wire can carry more current without overheating. That is why high-current circuits use thicker wires.
What is short circuit? Why is it dangerous?
A short circuit occurs when the live and neutral wires (or two points in a circuit with very different potentials) are connected directly with negligible resistance — often due to damaged insulation. This causes a very large current to flow (I = V/R; R ≈ 0, so I → very large). The huge current can melt wires, cause fires, and damage appliances. Fuses and MCBs protect against short circuits.
How is a fuse different from an MCB?
A fuse is a thin wire with low melting point that melts and breaks the circuit when excess current flows — it is destroyed and must be replaced. An MCB (Miniature Circuit Breaker) is an automatic electromagnetic switch that trips and breaks the circuit when current exceeds the safe limit — it can be reset by flipping the switch back up. MCBs are more reliable, faster, and reusable; fuses are cheaper. Modern Indian homes increasingly use MCBs.
Why does the resistance of a metallic conductor increase with temperature?
In metals, as temperature increases, the atoms vibrate with greater amplitude. This increases the frequency of collisions between free electrons (charge carriers) and the vibrating atoms, impeding the electron flow more. More collisions mean more opposition to current — higher resistance.