(English Medium) ICSE Class 10 - CISCE Question Bank Solutions

A family uses a light bulb of 100W, a fan of 100W, and a heater of 1000W, each for 8 hours a day. If the cost of electricity is Rs. 2 per unit, what is the expenditure to the family per day, on electricity?

Establish the relation that heat produced in a metallic conductor due to the flow of current is V²t/R joules, where V is the potential difference across the ends of the conductor, R its resistance and t is the time in second for which current flows.

Find the heat produced in joules when a current of 10 amperes flows through a connecting wire of resistance 2 × 10^-2 ohms and heating element of resistance 250 ohms for 2 seconds.

An electric lamp A of 40 W and another electric lamp B of 100 W are connected to 220 V supply. Calculate the ratio of their filament resistances?

Find the energy released by a current of 0.25 amperes flowing through a heater for 5 minutes. The p.d. is 230 V.

An electric iron is rated at 230 V, 750 W. What is its resistance? What maximum current can be passed through it?

An electric bulb is rated as 100W – 250V. What information does it convey? Calculate the resistance of its filament while glowing.

An electric bulb is rated as 100W – 250V. What information does it convey? Calculate the current through the filament of the bulb.

An Electric bulb is marked 100 W, 230 V. What find the energy consumed by the bulb in one hour.

An Electric bulb is marked 100 W, 230 V. What current does it take?

An Electric bulb is marked 100 W, 230 V. What how long would this lamp take to consume one unit of electricity?

Out of the three fuses with current ratings 5A, 10A, 15A, which one is to be connected in a geyser circuit marked 3 kW, 220V? Give reason for your answer.

The equation I²R seems to suggest that the rate of heating in a resistor is reduced if resistance decreases, whereas equation P = V²/R suggests just the opposite. How do you reconcile this problem?

Two resistances R₁ = 4Ω and R₂ = 6Ω are connected in series. The combination is connected with a battery of e.m.f. 6V and negligible resistance. Calculate:
(i) the heat produced per minute in each resistor,
(ii) the power supplied by the battery.

A bulb is connected to a battery of e.m.f. 6V and internal resistance 2Ω A steady current of 0.5A flows through the bulb. Calculate the total energy supplied by the battery in 10 minutes.

A bulb is connected to a battery of e.m.f. 6V and internal resistance 2Ω A steady current of 0.5A flows through the bulb. Calculate the resistance of the bulb.

A bulb is connected to a battery of e.m.f. 6V and internal resistance 2Ω A steady current of 0.5A flows through the bulb. Calculate the heat energy dissipated in the bulb in 10 minutes.

A battery of e.m.f. 12V and internal resistance 1.6 Ω is connected to two resistors of 4Ω and 6Ω connected in parallel. Calculate:
(i) the current drawn from the battery,
(ii) the power dissipated in each resistor,
(ii)the total power supplied by the battery.

A bulb is marked 100W, 220V and an electric heater is marked 2000 W, 220 V.
(i) What is the ratio between the resistances of these two devices?
(ii) How does the power-voltage rating of a device help us to decide about the type of leads (connecting wires) to be used for it?
(iii) In which of the above two devices, a thicker connecting wire of lead is required?

An immersion rod having resistance of 50 Ω is connected to 220V main supply. Assuming that all the energy generated goes to heat the water, calculate the time taken to heat 5 kg water from 30°C to 100°C.