Assertion : Magnetic Resonance Imaging $(MRI)$ is a useful diagnostic tool for producing images of various parts of human body.

Reason : Protons of various tissues of the human body play a role in $(MRI)$.

When $\sqrt 3 $ $ampere$ current is passed in a tangent galvanometer, there is a deflection of $ 30° $ in it. The deflection obtained when $3$ $ampere$ current is passed, is…..$^o$

The error in measuring the current with a tangent galvanometer is minimum when the deflection is about…..$^o$

A tangent galvanometer has a coil with $50$ $turns$ and radius equal to $4$ $cm$. A current of $0.1 $ $A$ is passing through it. The plane of the coil is set parallel to the earth's magnetic meridian. If the value of the earth's horizontal component of the magnetic field is $7 \times {10^{ – 5}}$ $tesla$ and  ${\mu _0} = 4\pi \times {10^{ – 7}}\, weber/amp \times m$, then the deflection in the galvanometer needle will be…..$^o$

The time period of a vibration magnetometer is $T_0$. Its magnet is replaced by another magnet whose moment of inertia is $3$ $times$ and magnetic moment is $1/3$ of the initial magnet. The time period now will be