The magnetic needle of a tangent galvanometer is deflected at an angle $30^{\circ}$ due to a magnet. The…
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 $0.34 \times 10^{-4} \mathrm{~T}$ is along the plane of the coil. The magnetic intensity is
$1.96 \times 10^{-4} \mathrm{~T}$
$1.96 \times 10^4 \mathrm{~T}$
$1.96 \times 10^{-5} \mathrm{~T}$
$1.96 \times 10^5 \mathrm{~T}$.
Solution
Angle through which magnet is deflected $(\theta)=30^{\circ}$ and horizontal magnetic field $\left(B_H\right)=0.34 \times 10^{-4} \mathrm{~T}$. Magnetic intensity $=B_H \tan \theta=0.34 \times 10^{-4} \times \tan 30^{\circ}$ $=\left(0.34 \times 10^{-4}\right) \times 0.577=1.96 \times 10^{-5} \mathrm{~T}$.