A capacitor is connected across an a.c. source in a circuit. If a dielectric slab is inserted between the plates, then, in the circuit the
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → current increases because reactance decreases
A dielectric slab of dielectric constant K raises the capacitance, and a larger capacitance has a smaller capacitive reactance.
\( \displaystyle C' = \frac{K\varepsilon_0A}{d} = KC \quad (K\gt 1) \)
\( \displaystyle X_C = \frac{1}{\omega C} \Rightarrow X_C \text{ decreases} \)
\( \displaystyle I = \frac{V}{X_C} \Rightarrow I \text{ increases} \)
So the current increases because the reactance decreases.