Question

If a variable frequency ac source is connected to a capacitor then with decrease in frequency the displacement current will

• A. increase
• B. decrease
• C. remains constant
• D. first decrease then increase

Answer 1

Answer: (B)

Current through capacitor,
$I=\frac{E}{X_C}=\frac{E}{\frac{I}{\omega C}}$
$=\omega CE=2\pi \upsilon CE$ or $I\propto \upsilon$.
$\therefore$ decrease in frequency $\upsilon$ of ac source decreases the conduction current. As displacement current is equal to conduction current, decrease in $\upsilon$ decreases displacement current in circuit.