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Average induced emf when the field or flux through a coil changes in a given time

This type of question, asked 9 times: 4 May 2023 S2, 11 May 2024 S2, 14 May 2024 S1, 14 May 2024 S2, 19 Apr 2025 S2, 26 Apr 2025 S1, 13 Apr 2026 S2, 20 Apr 2026 S1, 12 May 2026 S2. All 9 questions below, oldest first.

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  1. Question 1

    4 May 2023 S2

    25
    A magnetic field of 2×10−22\times10^{-2} T acts at right angles to a coil of area 100 cm2^2 with 50 turns. The average e.m.f. induced in the coil is 0.1 V, when it is removed from the field in time t. The value of 't' is (in second)

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  2. Question 2

    11 May 2024 S2

    19
    A coil having effective area 'A' is held with its plane normal to a magnetic field of induction 'B'. The magnetic induction is quickly reduced to 25% of its initial value in 1 second. The e.m.f. induced in the coil (in volt) will be

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  3. Question 3

    14 May 2024 S1

    50
    A magnetic field of 2×10−22\times10^{-2} T acts at right angles to a coil of area 100 cm2100\,\text{cm}^2 with 50 turns. The average e.m.f. induced in the coil is 0.1 V, when it is removed from the field in time 't'. The value of 't' is

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  4. Question 4

    14 May 2024 S2

    44
    A coil having effective area AA is held with its plane normal to magnetic field BB. The magnetic induction is quickly reduced by 25% of its initial value in 2 seconds. Then the e.m.f. induced across the coil will be

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  5. Question 5

    19 Apr 2025 S2

    28
    The magnetic flux through a coil is 4×10−4 Wb4 \times10^{- 4}\text{ }Wb at time t=0t = 0. It reduces to 30%30\% of its original value in time tt second. If e.m.f. induced in the coil is 0.56 mV then the value of t is

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  6. Question 6

    26 Apr 2025 S1

    46
    A magnetic field 4×10−2 T4 \times10^{- 2}\text{ }T acts at right angles to a coil of area 100 cm2100{\text{ }cm}^{2} with 50 turns. The average e.m.f. induced in the coil is 0.1 V, when it is removed from the field in time ' tt '. The value of ' tt ' is

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  7. Question 7

    13 Apr 2026 S2

    136
    A conducting loop of radius 10/[π]1/210/[\pi]^{1/2} cm is placed perpendicular to a uniform magnetic field 0.50.5 T. The magnetic field is decreased to zero in 0.50.5 s at a steady rate. The induced emf in the circular loop at 0.250.25 s is

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  8. Question 8

    20 Apr 2026 S1

    135
    A coil of effective area 3 m23\ \mathrm{m^2} is placed at right angles to a magnetic field of induction 0.05 Wb/m20.05\ \mathrm{Wb/m^2}. If the field is decreased to 20%20\% of its original value in 1010 second, the e.m.f. induced in the coil will be

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  9. Question 9

    12 May 2026 S2

    136
    The coil of area 0.10.1 m2^2 has 10001000 turns. It is placed in a magnetic field of strength 5×10−45 \times 10^{-4} T. The average e.m.f. induced in the coil, if rotated through 1800180^0 in 0.10.1 s is (cos⁡0∘=1,cos⁡180∘=−1)(\cos 0^\circ = 1, \cos 180^\circ = -1)

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