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 xx4/3 -1.2 A,U =1/2 Li^2=1/2xx1.2 xx1.2^2=0.864`