If a brass bar is placed on a vibrating magnet, then its time period

A certain amount of current when flowing in a properly set tangent galvanometer, produces a deflection of $ 45°.$  If the current be reduced by a factor of $\sqrt 3 $, the deflection would

The bob of a simple pendulum is replaced by a magnet. The oscillations are set along the length of the magnet. A copper coil is added so that one pole of the magnet passes in and out of the coil. The coil is short-circuited. Then which one of the following happens

Two magnets are held together in a vibration magnetometer and are allowed to oscillate in the earth's magnetic field with like poles together, $12$ oscillations per minute are made but for unlike poles together only $4$ oscillations per minute are executed. The ratio of their magnetic moments is

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.....$^o$

The magnet of a vibration magnetometer is heated so as to reduce its magnetic moment by $19\%$. By doing this the periodic time of the magnetometer will