Question

A tangent galvanometer has a coil of $50$ turns and a radius of $20cms$. The horizontal component of the earth's field is$3\times {10}^{-5}T$. Find the current through the coil.

• A. $0.19A$
• B. $0.29A$
• C. $0.39A$
• D. none of these

Answer 1

Answer: (A)

$0.19A$

Given,
$B=3\times {10}^{-5}T$
$n=50$
$r=20cms=20\times {10}^{-2}m$
Taking $\theta ={45}^{\circ }$
$I=\frac{2rB}{{\mu }_{0}n}=\frac{2\times 20\times {10}^{-2}\times 3\times {10}^{-5}}{50\times 4\pi \times {10}^{-7}}=0.19A$