Tangent galvanometer is used to measure

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.)

A tangent galvanometer has a coil of $25$ $turns$ and radius of $15 \,cm.$ The horizontal component of the earth’s magnetic field is  $3 × 10^{-5}$ $T$. The current required to produce a deflection of $45^o$ in it, is…..$A$

$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

Vibration magnetometer is used for comparing