If the number of turns and the radius of the cross-section of the coil of a tangent galvanometer are both doubled,then the reduction factor $K$ will become:

The frequency of oscillation of a small magnet in a magnetic field of induction $B$ is $n$. If the frequency of oscillations of the same magnet in a field of induction $X$ falls to $n/3$, the value of $X$ is

The period of oscillation of a bar magnet at a place is $2 \,s$. At the same place, the period of oscillation of another identical bar magnet whose magnetic moment is $4$ times that of the first magnet is: (in $\,s$)

Which curve best represents the relationship between current $i$ and deflection $\theta$ in a tangent galvanometer?

$A$ short magnet oscillates with a frequency $10 \, Hz$ where the horizontal component of Earth's magnetic field is $12 \, \mu T$. $A$ downward current of $15 \, A$ is established in a vertical wire placed $20 \, cm$ west of the magnet. The new frequency of the magnet is (in $ \, Hz$)

$A$ vibration magnetometer works on the principle of