Question

A dip circle is so set that the dip needle moves freely in the magnetic meridian. In this position the angle of dip is ${39}^{\circ }$. Now the dip circle is rotated so that the plane in which the needle moves, makes an angle of ${30}^{\circ }$ with the magnetic meridian. In this position, the needle will dip by an angle :

• A. exactly ${39}^{\circ }$
• B. ${30}^{\circ }$
• C. more than ${39}^{\circ }$
• D. less than ${39}^{\circ }$

Answer 1

The correct option is C

more than ${39}^{\circ }$

$\frac{tan\delta }{tan{\delta }^{\prime }}=cos\alpha$

$tan{\delta }^{\prime }=\frac{tan\delta }{cos\alpha }$

$sincecos\alpha <1$

$=\frac{tan\delta }{cos\alpha }sincecos\alpha <1$

$\therefore tan{\delta }^{\prime }>tan\delta$

${\delta }^{\prime }>\delta$