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.....$sec$
$0.75$
$1.5$
$3$
$6$
If the number of turns and radius of cross section of the coil of a tangent galvanometer are doubled, then the reduction factor $K$ will become
Two magnets are held together in a vibration magnetometer and are allowed to oscillate in the earth's magnetic field with like poles together, $12$ oscillations per minute are made but for unlike poles together only $4$ oscillations per minute are executed. The ratio of their magnetic moments is
The number of turns and radius of cross-section of the coil of a tangent galvanometer are doubled. The reduction factor $K $ will be
The needle of a deflection galvanometer shows a deflection of $60^o $ due to a short bar magnet at a certain distance in $\tan A$ position. If the distance is doubled, the deflection is
The period of oscillation of a magnet of a vibration magnetometer is $2.45 \,s$ at one place and $4.9 \,s$ at the other. The ratio of the horizontal component of earth magnetic field at the two places is .........