[" A vibration magnetometer placed in magnetic "],[" meridian has a small bar magnet.The magnet "],[" executes oscillations with a time period 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 carrying wire,the new time period of "],[" magnet carrying wire,the new time period of "],[" magnet will be: "],[[" (1) "4s," (4) "3s]],[[" (3) "2s," (4) "3s,]]