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Heat produced: Joule's law calculations

This type of question, asked 4 times: 2022, 2023, 2024, 2025. All 6 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    2022

    12 (b)
    (i) State Joule’s law of heating. Express it mathematically when an appliance of resistance R is connected to a source of voltage V and the current I flows through the appliance for a time t. (ii) A 5 Ω5\,\Omega resistor is connected across a battery of 6 volts. Calculate the energy that dissipates as heat in 10 s.

  2. Question 2

    2023

    15
    The resistance of a resistor is reduced to half of its initial value. If other parameters of the electrical circuit remain unaltered, the amount of heat produced in the resistor will become :

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  3. Question 3

    2024

    14
    An electric iron of resistance 20 Ω20\,\Omega draws a current of 5 A. The heat developed in the iron in 30 seconds is :

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  4. Question 4

    2025

    22 (b)
    Calculate potential difference across a 4 Ω4\,\Omega resistor that produces 100 J of heat every second.

  5. Question 5

    2025

    22 (b)
    Heat produced per second due to a current in a resistor of 4 Ω4\,\Omega is 400 joules. Calculate the potential difference across the resistor.

  6. Question 6

    2025

    26
    A voltage source sends a current of 2 A to a resistor of 40 Ω40\,\Omega connected across it for 5 minutes. Calculate the electrical energy supplied by the source.