Question

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

• A. $0.864J$
• B. $0.72J$
• C. $0.173J$
• D. $1.44J$

Answer 1

The correct option is A $0.864J$

Current $=$ reduction factor X deflection
$=0.9\times \tan {53}^o$
$=0.9\times \frac{4}{3}$
$=1.2A$
Energy $=\frac{L{i}^2}{2}$
$=\frac{1}{2}\times 1.2\times (1.2{)}^2$
$=0.864J$