Physics - Capacitor Question with Solution | TestHub

When a dielectric material is placed in an external electric field ${\vec{E}}_0$, the molecules of the dielectric get polarized. This polarization induces an internal electric field ${\vec{E}}_p$ which opposes the external electric field.

The net electric field inside the dielectric is given by $\vec{E}={\vec{E}}_0-{\vec{E}}_p$.

Since the induced electric field ${\vec{E}}_p$ is in the opposite direction to ${\vec{E}}_0$, the magnitude of the net electric field inside the dielectric is $E=E_0-E_p$.

Alternatively, the electric field inside a dielectric is $E=\frac{E_0}{K}$, where $K$ is the dielectric constant. Since $K>1$ for all dielectrics, $E<E_0$.

Thus, the electric field inside the dielectric is always less than the external electric field.

Answer: less than the external electric field.