Question

The magnetic field at the centre of the circular coil carrying current of 4A is

• A. $\frac{8\pi }{3}\times {10}^{-5}T$
• B. $\frac{8\pi }{3}\times {10}^{-4}T$
• C. $2\pi \times {10}^{-5}T$
• D. $2\pi \times {10}^{-4}T$

Answer 1

The correct option is C $2\pi \times {10}^{-5}T$

$B=\frac{{\mu }_{0}i}{2r}\left[\frac{\theta }{2\pi }\right]=\frac{4\pi {10}^{-7}\times 4}{2\times 3\times {10}^{-2}}\left[\frac{\frac{3\pi }{2}}{2\pi }\right]=2\pi \times {10}^{-5}T$