Ncert Exercises & Solutions

A variable frequency AC source is connected to a capacitor. How will the displacement current change with a decrease in frequency?

Hint: The displacement current depends on the reactance of the capacitor.

Step 1: Find the capacitive reactance.

Capacitive reactance,

X_{c} = \frac{1}{2 πfC}

X_{c} \propto \frac{1}{f}

Step 2: Find the displacement current.

As frequency decreases,

X_{c}

increases and the conduction current is inversely proportional to

X_{c} (∵ l \propto \frac{1}{X_{c}})

So, the displacement current decreases as the conduction current is equal to the displacement current.