A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip pointing down at `22^@` with the horizontal . The horizontal component of the earth's magnetic field at the place is known to be 0.35 G . Determine the magnitude of the earth's magnetic field at the place.

Explanation

`theta=22^@,H_E=0.35xx10^(-4)T,B_E=`?
`H_E=B_Ecostheta,:.B_E=H_E/(costheta)=(0.35xx10^(-4))/(cos22^@)=0.38xx10^(-4)T " or " 0.38 G`