Question

A dielectric slab of thickness $d$ is inserted in a parallel plate capacitor whose negative plate is at $x=3d$. The slab is equidistant from the plates. The capacitor is given some charge. As $x$ goes from $0$ to $3d$ :

• A. the magnitude of the electric field remains the same
• B. the direction of the electric field remains the same
• C. the electric potential increases continuously
• D. the electric potential increases at first, then decreases and again increases

Answer 1

Answer: (B), (D)

As $x$ from $0-3d$

1) Magnitude of $\overrightarrow{E}$ changes due to dielectric slab. In region A and C is same but not in B

2) the direction of $\overrightarrow{E}$ remains same throughout in all regions A,B,C

3) Electric potential also changes, since electric field varies, so potential also changes.

4) Electric potential first increases and then decreases due to dielectric slab and then again increases.