Question

A coil of 40 Ω resistances has 100 turns and radius 6 mm is connected to ammeter of resistance of 160 ohms. Coil is placed perpendicular to the magnetic field. When coil is taken out of the field, 32 μ C charge flows through it. The intensity of magnetic field will be

• A. 6.55 T
• B. 5.66 T
• C. 0.655 T
• D. 0.566 T

Answer 1

Answer: (D)

0.566 T

Answer 2

$q = - \frac{N}{R}\left( B_{2} - B_{1} \right)A\cos\theta$

$32 \times 10^{- 6} = - \frac{100}{(160 + 40)}(0 - B) \times \pi \times \left( 6 \times 10^{- 3} \right)^{2} \times \cos 0^{o}$

$\Rightarrow B = 0.565\mspace{6mu} T$