Question

If a current of 500 mA produces a deflection of $30^\circ$ in a tangent galvanometer, then the current that produces a deflection of $60^\circ$ is

• A. 1. 5 A
• B. 1 A
• C. 500 mA
• D. 866 mA

Answer 1

Answer: (A)

1. 5 A

Answer 2

If an electric current I is flowing through the coil of the tangent galvanometer and the magnetic needie gets deflected and comes to rest making an angie $\theta$ with the direction of horizontaI component of earth's magnetic field H, then for the tangent galvanometer
$I = K \tan \theta$
where K is the reduction factor of tangent galvanometer.
$\therefore \, \frac{I_1}{I_2} = \frac{tan \,\theta_1}{\tan \theta_2}$
or $\frac{500}{I_2} = \frac{\tan 30^\circ}{\tan 60^\circ}$ or $\frac{500}{I_2} = \frac{\bigg(\frac{1}{\sqrt{3}}\bigg)}{\sqrt{3}}$
or $\frac{500}{I_2} = \frac{1}{3}$
or $I_2 = 1500 \,mA = 1.5\, A$