Question
42.A vibration magnetometer placed jn a magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of of 2s in earth's horizontal magnetic field of 24 microtesla . When a horizontal field of 18 microtesla is produced opposite to the earth's field by placing a current carryi g wire , the new time period of magnet will be:- 1) 4s 2) 1s 3) 2s 4) 3s