Two different magnets are tied together and allowed to vibrate in a horizontal plane. When their like poles are joined, time period of oscillation is $5 \,s$ and with unlike poles joined, time period of oscillation is $15 \,s$. The ratio of their magnetic moments is

When $\sqrt 3 $ $ampere$ current is passed in a tangent galvanometer, there is a deflection of $ 30° $ in it. The deflection obtained when $3$ $ampere$ current is passed, is…..$^o$

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

A vibration magnetometer placed in magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of $2\, sec$ in the earth's horizontal magnetic field of $24$ $microtesla$ . When a horizontal field of $18$ $microtesla$ is produced opposite to the earth's field by placing a current carrying wire, the new time period of magnet will be….$s$

The sensitivity of a tangent galvanometer is increased if