Moving Charges And Magnetism Ques 42

42. Magnetic field intensity at the centre of a coil of $50$ turns, radius $0.5 $ $ m$ and carrying a current of $2 $ $A$ is

[1999]

(a) $0.5 \times 10^{-5} $ $ T$

(b) $1.25 \times 10^{-4} $ $ T$

(c) $3 \times 10^{-5} $ $ T$

(d) $4 \times 10^{-5} $ $ T$

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Answer:

Correct Answer: 42.(b)

Solution:

  1. (b) We know that magnetic field at the centre of circular coil,

$B=\frac{\mu_0 I n}{2 r}=\frac{4 \pi \times 10^{-7} \times 2 \times 50}{2 \times 0.5}=1.25 \times 10^{-4}$ $ N$