A dielectric slab of thickness `d` is inserted in a parallel plate capacitor whose negative plate is at `x=0` and positive plate is at `x = 3d`. The slab is equidistant from the plates. The capacitor is given some charge. As one goes from `0` to `3d(1998)`.

Options

A. (a) the magnitude of the electric field remains the same.
B. (b) the direction of the electric field remains the same.
C. (c) the electric potential increases continuously.
D. (d) the electric potential increases at first, then decreases and again increases.

Answer

B, C

Explanation

In region I and III, there will be electric field `vecE_0` directed from positive to negative. In region II, due to orientation of dipoles, there is an electric field `vecE_k` present in opposite direction of `vecE_0`. But since `vecE_0` is also present, the net electric field is `vecE_0-vecE_k` in the direction of `vecE_0` as shown in the diagram. `(:' E_0gtE_k)`