Two parallel metal plates having charges $+Q$ and $-Q$ face each other at a certain distance between them. If the plates are now dipped in kerosene oil tank, the electric field between the plates will

• A

  become zero
• B

  increase
• Correct answer
  C

  decrease
• D

  remain same

Solution

The electric field in vacuum $$ \mathrm{E}_0=\frac{\sigma}{2 \varepsilon_0} $$ When the plates are dipped in kerosene oil tank, then the electric field between the plate will be $$ \begin{array}{rlrl} & & \mathrm{E} & =\frac{\sigma}{2 \varepsilon_0 \mathrm{k}} \\ \because & \mathrm{k} & >1 \\ \therefore & & \mathrm{E} & < \mathrm{E}_0 \end{array} $$ So, the electric field between the plates will decrease.

Hence, the correct answer is option: 'C'.