Question

A deflection magnetometer works on
A) Coulomb’s Law
B) Tangent Law
C) Curie Law
D) The law of vibration of magnet.

Answer 1

Hint : Magnetometers are used to determine the presence of magnetic fields .It is done so by the angular movement of the free bar magnet which is pivoted in the horizontal plane. It consists of a compass box in which a small magnetic needle is pivoted at the center of the circular scale, in such a way that the needle is allowed to freely rotate in the horizontal plane. This compass box is placed at the center of a long 1m wooden box.

Complete step by step answer
Deflection Magnetometer works on the principle of tangent Law. According to tangent law when two uniform magnetic field act at right angles to each other on a magnetic needle, it comes to rest in the direction of the resultant field.$B = {B_H}\tan \theta $,$B$is the magnetic induction due to the bar magnet ,${B_H}$ is the horizontal earths component of magnetic field and$\theta $ is the angle through which the needle has moved.
 We know that earth has a horizontal component of magnetic field denoted ${B_H}$.Its magnetic field lies in the horizontal plane and its normal passes through the center of the earth. The magnetic dipole moment of the magnet is the property which helps the magnet to align parallel in the direction of the external magnetic field. The unit of magnetic dipole moment is ampere-square meters$A{m^2}$.

Note: Deflection magnetometer is used to compare magnetic moments as well as the earth’s magnetic induction. Inverse square law can be verified using the deflection magnetometer. The horizontal component of the earth’s magnetic field can be calculated using the deflection magnetometer.