Two tangent galvanometer coils of same radius connected in series. The current flowing produces deflection of $60^o$ and $45^o$. The ratio of number of turns in coil is

A magnetic needle is made to vibrate in uniform field $H$, then its time period is $T$. If it vibrates in the field of intensity $4H, $ its time period will be

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 $(MRI)$.

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 $45^o$.

The radius of the coil of a Tangent galvanometer. which has $ 10 $ $turns$ is $0.1\,m. $ The current required to produce a deflection of $60°$  $({B_H} = 4 \times {10^{ – 5}}\,T)$ is…..$A$