Question

A galvanometer coil bas 500 turns and each tum has an average area of 3 × 10^-4 m². If a torque of 1.5 Nm is required to keep this coil parallel to a magnetic field when a current of 0.5 A is flowing through it, the strength of the field (in T) is ______.

विकल्प

• 10

• 20

• 30

• 40

Answer 1

A galvanometer coil bas 500 turns and each tum has an average area of 3 × 10^-4 m². If a torque of 1.5 Nm is required to keep this coil parallel to a magnetic field when a current of 0.5 A is flowing through it, the strength of the field (in T) is 20.

Explanation:

Given,

Area of galvanometer coil, A = 3 × 10^-4 m²

Number of turns in the coil, N = 500

Current the coil, I = 0.5 A

Torque τ = ${\displaystyle |\overrightarrow{\text{M}}\times \overrightarrow{\text{B}}|}$ = NiAB sin (90°) = NiAB

⇒ B = ${\displaystyle \frac{\tau }{\text{NiA}}}$

= ${\displaystyle \frac{1.5}{500\times 0.5\times 3\times {10}^{-4}}}$

= 20 T