A tangent galvanometer has a coil with 50 turns and radius equal to 4 cm . A current of 0.1 A is passing through it. The plane of the coil is set parallel to the earth's magnetic meridian. If the value of the earth's horizontal component of the magnetic field is `7xx10^(-5)` Tesla and `mu_(0)=4pixx10^(-7)Weber//ampxxm` then the deflection in the galvanometer needle will be

Options

A. `45^(@)`
B. `48.2^(@)`
C. `50.7^(@)`
D. `52.7^(@)`

Answer

B

Explanation

`i= (2rB_H)/(mu_0 n ) tan theta`
`tan theta = (mu_0 ni)/(2rB) = (4 pi xx 10^(-7) xx 50 xx 0.1)/(2 xx 0.04 xx 7 xx 10^(-5)) = 1.121`
`implies theta = 48.2 ^(@)`