Q. A dip needle vibrates in the vertical plane perpendicular to magnetic meridian. The time period of vibration is found to be 2 s. The same needle is then allowed to vibrate in the horizontal plane and time period is again found to be 2s. Then the angle of dip is
A) 0${^\circ}$
B) 30${^\circ}$
C) 45${^\circ}$
D) 90${^\circ}$
Explanation
(c) $T_{1} = 2\pi\sqrt{\frac{I}{MV}}$
$T_{2} = 2\pi\sqrt{\frac{I}{MH}}$
$\ \frac{T_{2}}{T_{1}} = \sqrt{\frac{V}{H}}$=$\sqrt{tan\theta}$
or $tan\theta$=$\left( \ \frac{T_{2}}{T_{1}} \right)^{2} = \left( \frac{2}{2} \right)^{2} = 1$
$\theta = 45{^\circ}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.