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 $7 \times {10^{ - 5}}tesla$ tesla and ${\mu _0} = 4\pi \times {10^{ - 7}}weber/amp \times m$, then the deflection in the galvanometer needle will be