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
increase by $19\%$
decrease by $19\%$
increase by $11\%$
decrease by $21\%$
A magnetic needle is made to vibrate in uniform field $H$, then its time period is $T$. If it vibrates in the field of intensity $4H, $ its time period will be
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
If a brass bar is placed on a vibrating magnet, then its time period
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
The time period of oscillation of a magnet in a vibration magnetometer is $1.5$ seconds. The time period of oscillation of another magnet similar in size, shape and mass but having one-fourth magnetic moment than that of first magnet, oscillating at same place will be.....$sec$