Question

For the series LCR circuit as shown in figure, the heat developed in 80 s and amplitude of wattless current is :

• A. $4000J,3A$
• B. $8000J,3A$
• C. $4000J,4A$
• D. $8000J,5A$

Answer 1

The correct option is A $4000J,3A$

$z=\sqrt{R^2+(X_L-X_C{)}^2}$

$=\sqrt{4^2+(7-4{)}^2}=5ohm$

Heat $=i_{max}RT$

$=\frac{125\times 4\times 80}{2}=40005$

$\cos \varphi =\frac{R}{2}=\frac{4}{5},\varphi ={37}^o$

watt less current, $I_{rms}\sin \varphi =3A$