Q. In a parallel plate capacitor the separation between the plates is $3\ mm$ with air between them. Now a $1mm$ thick layer of a material of dielectric constant 2 is introduced between the plates due to which the capacity increases. In order to bring its capacity to the original value the separation between the plates must be made
A) $1.5\ mm$
B) $2.5\ mm$
C) $3.5\ mm$
D) $4.5\ mm$
Explanation
(c) $K = \frac{t}{t - d'} \Rightarrow 2 = \frac{1}{1 - d'} \Rightarrow d^{'} = \frac{1}{2}mm$
So new distance $= 3 + \frac{1}{2} = 3.5\ mm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.