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Current Electricity question

2023 · 31 Jan · Shift 2 · Q51
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  5. /2023 · 31 Jan · Shift 2 · Q51

Current Electricity question

2023 · 31 Jan · Shift 2 · Q51

JEE MainPhysicsCurrent ElectricityMCQ+4 / −1
The H\mathrm{H}H amount of thermal energy is developed by a resistor in 10 s10 \mathrm{~s}10 s when a current of 4 A4 \mathrm{~A}4 A is passed through it. If the current is increased to 16 A16 \mathrm{~A}16 A, the thermal energy developed by the resistor in 10 s10 \mathrm{~s}10 s will be :
  1. A
    H4\frac{\mathrm{H}}{4}4H​
  2. B
    16H16 \mathrm{H}16H
  3. C
    H
  4. D
    4H4 \mathrm{H}4H
View written solutionFree

Correct answer: B

  1. Use Joule’s law of heating

    The thermal energy developed in a resistor is Q=I2RtQ = I^2 R tQ=I2Rt where:

    • QQQ = heat produced,
    • III = current,
    • RRR = resistance,
    • ttt = time.
  2. First case

    When current I1=4 AI_1 = 4\,\text{A}I1​=4A flows for t=10 st=10\,\text{s}t=10s, the heat produced is given as HHH.

    So, H=(4)2R(10)H = (4)^2 R (10)H=(4)2R(10)

  3. Second case

    Now current is increased to I2=16 AI_2 = 16\,\text{A}I2​=16A, with the same resistor and same time t=10 st=10\,\text{s}t=10s.

    Let the new heat produced be Q2Q_2Q2​.

    Q2=(16)2R(10)Q_2 = (16)^2 R (10)Q2​=(16)2R(10)

  4. Take ratio

    Q2H=(16)2R(10)(4)2R(10)\frac{Q_2}{H} = \frac{(16)^2 R (10)}{(4)^2 R (10)}HQ2​​=(4)2R(10)(16)2R(10)​

    Cancelling common factors: Q2H=16242=(164)2=42=16\frac{Q_2}{H} = \frac{16^2}{4^2} = \left(\frac{16}{4}\right)^2 = 4^2 = 16HQ2​​=42162​=(416​)2=42=16

    Therefore, Q2=16HQ_2 = 16HQ2​=16H

  5. Check options

    • A: H4\frac{H}{4}4H​ ❌
    • B: 16H16H16H ✅
    • C: HHH ❌
    • D: 4H4H4H ❌

Hence, the correct answer is Option B.

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