A solenoid of self inductance `1.2 H` is in series with a tangent galvanonmeter of reduction factor `0.9 A`.They are connected to a battery and the tangent galvanometer shows a deflection of `53^(@)`. The energy stored in the magnetic field of the solenoid is `(tan 53^(@) = 4//3)`

Options

A. `0.864 J`
B. `0.72 J`
C. `0.173 J`
D. `1.44 J`

Answer

A

Explanation

`I = K tan theta = 0.9 xx (4)/(3) = 1.2, U = (1)/(2) Li^(2) = (1)/(2) xx 1.2 xx 1.2^(2) = 0.864`