The time period of a vibration magnetometer is $T_0$. Its magnet is replaced by another magnet whose moment of inertia is $3$ times and magnetic moment is $1/3$ of the initial magnet. The time period now will be

Two tangent galvanometer coils of same radius connected in series. The current flowing produces deflection of $60^o$ and $45^o$. The ratio of number of turns in coil is

$A $ magnet freely suspended in a vibration magnetometer makes $10 $ oscillations per minute at a place $A$  and $20 $ oscillations per minute at a place $B$. If the horizontal component of earth’s magnetic field at $A$ is $36 \times {10^{ – 6}}\,T$, then its value at $B$ is

A short bar magnet placed in a horizontal plane has its axis aligned along the magnetic north-south direction. Null points are found on the axis of the magnet at $14\; cm$ from the centre of the magnet. The earth's magnetic field at the place is $0.36\; G$ and the angle of $dip$ is zero. What is the total magnetic field (in $G$) on the normal bisector of the magnet at the same distance as the null-point (i.e., $14 \;cm$) from the centre of the magnet? (At null points, field due to a magnet is equal and opposite to the horizontal component of earth's magnetic field.)

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