A vibration magnetometer placed in a magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of in the earth's horizontal magnetic field of microteslas. When a horizontal field of microteslas is produced opposite to the earth's field by placing a current-carrying wire, the new time period of the magnet will be
Step 1: Given data
The magnet executes oscillations with a time period of .
The earth's horizontal magnetic field of microteslas.
A horizontal field of microteslas.
Step 2: To find
We have to determine the new time period of the magnet.
Step 3: Calculation
We know that,
The time period T of oscillation of a magnet is:
l is the moment of inertia of the magnet about the axis of rotation.
M is the magnetic moment of the magnet.
B is the uniform magnetic field as l, remains the same.
Therefore, option D is the correct choice.