A dip needle vibrates plane perpendicular to magnetic meridian. The time of vibration is found to be 25, the same needle is then allowed to vibrate in the horizontal plane and the time period is again found to be 25. Then, the angle of dip is

Options

A. `0^@`
B. `30^@`
C. `45^@`
D. `90^@`

Answer

3

Explanation

In vertical plane perpendicular to magnetic meridian `T=2pi sqrt(1/MB_(v))` ….(i)
In horizontal plane `T= 2pi sqrt(1/MB_(B))` …..(ii)
Equation (i) and (ii) gives `B_(v) =B_(B)`,
Hence by using `tan phi =B_(v)/B_(H) rArr tan phi=1 rArr phi =45^@`