Question

Same current is flowing in two a.c. circuits. First contains only inductance and second contains only capacitance. If frequency of a.c. is increased for both, the current will

• A. Increase in first circuit and decrease in second
• B. Increase in both circuits
• C. Decrease in both circuits
• D. Decrease in first circuit and increase in second

Answer 1

The correct option is D Decrease in first circuit and increase in second

Inductive circuit :
Inductive reactance $X_L=2\pi fL$
Current $I=\frac{V_o}{X_L}=\frac{V_o}{2\pi fL}$
$⟹I\propto \frac{1}{f}$
Thus current decreases in the inductive circuit is the frequency is increased.
Capacitive circuit :
Capacitive reactance $X_C=\frac{1}{2\pi fC}$
Current $I=\frac{V_o}{X_C}=2\pi fC{V}_o$
$⟹I\propto f$
Thus current increases in the capacitive circuit is the frequency is increased.