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Field at the centre of a revolving charge or rotating charged ring

This type of question, asked 7 times: 3 May 2023 S1, 3 May 2023 S2, 4 May 2023 S2, 12 May 2024 S2, 19 Apr 2025 S2, 15 Apr 2026 S2, 14 May 2026 S2. All 7 questions below, oldest first.

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  1. Question 1

    3 May 2023 S1

    45
    A particle having charge 50e is revolving in a circular path of radius 0.4 m with 1 r.p.s. The magnetic field produced at the centre is [μ0=4π×10−7, e=1.6×10−19 C\mu_0=4\pi\times10^{-7},\ e=1.6\times10^{-19}\ \text{C}]

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  2. Question 2

    3 May 2023 S2

    2
    A thin ring of radius 'RR' carries a uniformly distributed charge. The ring rotates at constant speed 'NN' r.p.s. about its axis perpendicular to the plane. If 'BB' is the magnetic field at the centre, the charge on the ring is (μ0=\mu_{0}= permeability of free space)

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  3. Question 3

    4 May 2023 S2

    15
    A particle carrying a charge equal to 100 times the charge on an electron is rotating one rotation per second in a circular path of radius 0.8 m. The value of magnetic field produced at the centre will be (μ0=\mu_0 = permeability of vacuum)

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  4. Question 4

    12 May 2024 S2

    7
    An electron makes a full rotation in a circle of radius 0.8 m in one second. The magnetic field at the centre of the circle is (μ0=4π×10−7\mu_0 = 4\pi \times 10^{-7} SI units)

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  5. Question 5

    19 Apr 2025 S2

    4
    A particle carrying a charge equal to 1000 times the charge on an electron, is rotating one rotation per second in a circular path of radius ' rr ' mm. If the magnetic field produced at the centre of the path is xx times the permeability of vacuum, the radius ' r ' in m is [e=1.6×10−19C][x=2×10−16]\left\lbrack e = 1.6 \times10^{- 19}C \right\rbrack\left\lbrack x = 2 \times10^{- 16} \right\rbrack

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  6. Question 6

    15 Apr 2026 S2

    134
    A thin ring of radius 'R' metre has charge 'q' coulomb uniformly spread on it. The ring rotates about its axis with a constant frequency of 'f' revolution/s. The value of magnetic induction at the centre of the ring in Wb/m2\mathrm{Wb/m^2} is ( μ0\mu_0 = permeability of free space )

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  7. Question 7

    14 May 2026 S2

    131
    A particle carrying a charge equal to 100100 times the charge of an electron is rotating one rotation per second in a circular path of radius 0.80.8 m. The value of magnetic field produced at the centre will be (μ0\mu_0 = permeability of free space)

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