Magnets $A$ and $B$ are geometrically similar but the magnetic moment of $A$ is twice that of $B$. If $T_1 $ and $T_2$ be the time periods of the oscillation when their like poles and unlike poles are kept together respectively, then $\frac{{{T_1}}}{{{T_2}}}$will be

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.If the bar magnet is turned around by $180^o$, where will the new null points (in $cm$) be located?

Two tangent galvanometers having coils of the same radius are connected in series. A current flowing in them produces deflections of $60° $ and $45°$  respectively. The ratio of the number of turns in the coils is

The radius of the coil of a Tangent galvanometer. which has $ 10 $ $turns$ is $0.1\,m. $ The current required to produce a deflection of $60°$  $({B_H} = 4 \times {10^{ - 5}}\,T)$ is.....$A$

Time period in vibration magnetometer will be infinity at

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