A dip needle vibrates in the vertical plane perpendicular to the magnetic meridian. The time period of vibration is found to be 2 sec. The same needle is then allowed to vibrate in the horizontal plane and the time period is again found to be 2 seconds. Then the angle of dip is

Options

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

Answer

C

Explanation

In vertical plane perpendicular to magnetic meridian.
`T=2pisqrt(I/(MB_(V))) …(i)`
In horizontal plane
`T=2pisqrt(I/(MB_(H))) ...(ii)`
Equations (i) and (ii) give `B_(V)=B_(H)`
Hence, by using `tan varphi=B_(V)/B_(H)implies tan varphi=1impliesvarphi=45^(@)`