Vibration magnetometer before use, should be set
In magnetic meridian
In geographical meridian
Perpendicular to magnetic meridian
In any position
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
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.)
Twists of suspension fibre should be removed in vibration magnetometer so that
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
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