Question

The magnetic needle of a tangent galvanometer is deflected at an angle $30^{\circ}$ due to a magnet. The horizontal component of earth's magnetic field $0.34$ $\times 10^{-4} T$ is along the plane of the coil. The magnetic intensity is

• A. $1.96 \times 10^{-4} T$
• B. $1.96 \times 10^{4} T$
• C. $1.96 \times 10^{-5} T$
• D. $1.96 \times 10^{5} T$

Answer 1

Answer: (C)

$1.96 \times 10^{-5} T$

Answer 2

Angle through which magnet is deflected $( \theta )=30^{\circ}$ and horizontal magnetic field $\left( B _{ H }\right)=0.34 \times 10^{-4} T$. Magnetic intensity $= B _{ H } \tan\,\theta$ $=0.34 \times 10^{-4} \times \tan 30^{\circ}$ $=\left(0.34 \times 10^{-4}\right) \times 0.577$ $=1.96 \times 10^{-5} T$