Question

A parallel plate capacitor is immersed in an oil of dielectric constant $2$. The field between the plates is:

• A. decreased proportional to $\frac{1}{\sqrt{2}}$
• B. increased proportional to $2$
• C. increased proportional to $\sqrt{2}$
• D. decreased proportional to $\frac{1}{2}$

Answer 1

Answer: (D)

When a dielectric material is inserted between the plates of a capacitor (keeping the charge to be constant) or capacitor is immersed in dielectric medium, the electric field decreases by a factor $k$ (the dielectric constant of the dielectric)
$\therefore E=\frac{E_0}{k}$
Given, $k=2$ Hence, $E=\frac{E_0}{2}$
Thus, electric field between the plates is decreased proportional to $\frac{1}{2}$.