If magnetic lines of force are drawn by keeping a magnet vertical,then the number of neutral points will be

$A$ bar magnet is placed on a table along the east-west direction in the Earth's magnetic field. The number of neutral points,where the magnetic field is zero,is

If a brass bar is placed on a vibrating magnet, then its time period

$A$ bar magnet of $10 \,cm$ length is kept with its north $(N)$-pole pointing north. $A$ neutral point is formed at a distance of $15 \,cm$ from each pole. Given the horizontal component of Earth's magnetic field is $0.4 \,Gauss$, the pole strength of the magnet is: (in $\,A-m$)

$A$ vibration magnetometer works on the principle of

The time period in a vibration magnetometer will be infinity at