A certain amount of current when flowing in a properly set tangent galvanoment, produces a deflection of `45^(@)`. If the current be reduced by a factor of `sqrt(3)`, the deflection would

Options

A. Decrease by `30^(@)`
B. Decrease by `15^(@)`
C. Increase by `15^(@)`
D. Increase by `30^(@)`

Answer

B

Explanation

In tangent galvanometer, `I prop tan theta`
:. `I_(1)/I_(2)=(tantheta_(1))/(tantheta_(2)) impliesI_(1)/(I_(1)//sqrt(3))=(tan 45^(@))/(tantheta_(2))`
`implies sqrt(3)tantheta_(2)=1 implies tantheta_(2)= 1/sqrt(3) implies theta_(2)=30^(@)`
So deflection will decrease by `45^(@)-30^(@)=15^(@)`