Question

A dielectric slab is inserted between the plates of an isolated capacitor. The force between the plates will

• A. increase
• B. remain unchanged
• C. decrease
• D. become zero

Hint:

Inserting a dielectric increases capacitance but decreases the force between the plates, as the electric field is reduced.

Answer 1

The Correct Option is C

Step 1: Dielectric Effect on Capacitance.
A dielectric inserted between capacitor plates increases capacitance by the factor \( \kappa \). For an isolated capacitor, \(Q\) is constant.
Step 2: Capacitor Plate Force.
The force \(F\) between capacitor plates is: \[F = \frac{1}{2} \frac{Q^2}{A \epsilon_0} \left( \frac{1}{d^2} \right)\] Inserting a dielectric reduces the electric field and, consequently, the force between the plates.Step 3: Final Result.
The force between the plates decreases.
Final Answer: \[ \boxed{\text{decrease}} \]