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Resistance and current from a power rating

This type of question, asked 5 times: 2022, 2023, 2024, 2025, 2026. All 7 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    2022

    4 (a)
    An electric heater rated 1100 W operates at 220 V. Calculate (i) its resistance, and (ii) the current drawn by it.

  2. Question 2

    2023

    36
    (a) An electric iron consumes energy at a rate of 880 W when heating is at the maximum rate and 330 W when the heating is at the minimum. If the source voltage is 220 V, calculate the current and resistance in each case. (b) What is heating effect of electric current ? (c) Find an expression for the amount of heat produced when a current passes through a resistor for some time.

  3. Question 3

    2024

    32
    A 2000 W heater has a resistance of about 25 Ω25\,\Omega, whereas a 100 W bulb has a resistance of 500 Ω500\,\Omega. When 220 V is applied on these, then which of the two (a) can carry large currents ? (b) may be used with an electrical circuit having 1⋅01{\cdot}0 A rating ? (c) will be fitted with a 15 A electric board and not with a 5 A electric board ? Justify your answer in each case.

  4. Question 4

    2025

    26
    An electric kettle is rated 230 V; 1000 W. Calculate the resistance of its heating element when in operation.

  5. Question 5

    2025

    13
    An electric bulb is rated 220 V; 11W. The resistance of its filament when it glows with a power supply of 220 V is :

    Tap an option to check your answer.

  6. Question 6

    2025

    14
    An electric bulb is connected to a power supply of 220 V. If the current drawn by the bulb from the supply is 500 mA, the power of the bulb is :

    Tap an option to check your answer.

  7. Question 7

    2026

    34 (b)
    An electric heater is rated 220 V; 11 A. Calculate the power consumed if the heater is operated at 200 V.