At two places $ A $ and $B$ using vibration magnetometer, a magnet vibrates in a horizontal plane and its respective periodic time are $2$ $sec$ and $3$ $sec$ and at these places the earth's horizontal components are $H_A$ and $H_B$ respectively. Then the ratio between $H_A$ and $H_B$ will be
$9:4$
$3:2$
$4:9$
$2:3$
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
Twists of suspension fibre should be removed in vibration magnetometer so that
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
If a brass bar is placed on a vibrating magnet, then its time period
A tangent galvanometer has a coil of $100$ $turns$ and a radius of $20\,cm$. The horizontal component of the earth's magnetic field is $B_H = 3\times10^{-5}\,T$. Find the current which gives a deflection of $45^o$.