A bar magnet $A$ of magnetic moment $M_A$ is found to oscillate at a frequency twice that of magnet $B$ of magnetic moment $M_B$ when placed in a vibrating magneto-meter. We may say that

A long vertical wire in which a current is flowing produces a neutral point with the earth's magnetic field at a distance of $5\, cm$ from the wire. If the horizontal component of the earth's magnetic induction is $0.18\, gauss$, then the curent in the wire is......$A$

The length of a magnet is large compared to its width and breadth. The time period of its oscillation in a vibration magnetometer is $2 \,s. $ The magnet is cut along its length into three equal parts and three parts are then placed on each other with their like poles together. The time period of this combination will be

$A $ magnet freely suspended in a vibration magnetometer makes $10 $ oscillations per minute at a place $A$  and $20 $ oscillations per minute at a place $B$. If the horizontal component of earth’s magnetic field at $A$ is $36 \times {10^{ - 6}}\,T$, then its value at $B$ is

Two different magnets are tied together and allowed to vibrate in a horizontal plane. When their like poles are joined, time period of oscillation is $5 \,s$ and with unlike poles joined, time period of oscillation is $15 \,s$. The ratio of their magnetic moments is

Vibration magnetometer is used for comparing