The angle of dip if dip needleoscillating in vertical plane makes 40 oscillations per min in a magnetic meridian and 30 oscillations per minute in vertical plane at right angle to the magnetic meridian is

Options

A. `theta=sin^(-1)(0.5625)`
B. `theta=sin^(-1)(0.325)`
C. `theta=sin^(-1)(0.425)`
D. `theta=sin^(-1)(0.235)`

Answer

A

Explanation

`T=2pisqrt(1)/(MB) or T' =2pisqrt(I)/(mv)'`
B=Total earth's field intensity
v= vertical component of B
`T'/T=sqrt(B)/(V)rArr(T)^(2)/(t6(2)=B/V`
but `V=BsinthetarArr(T')/(T^(2))=(1)/(sintheta)rArrsintheta=(T^(@))/(T'^(2))`
`T=60/40=(3)/(2)S`
Also, and `T'=60/30=2s`
`therefore sintheta=0.5625 rArr=sin^(-1)(0.5625)`