Q. The plates of a parallel plate capacitor are charged up to 100 V. A 2 mm thick plate is inserted between the plates, then to maintain the same potential difference, the distance between the capacitor plated is increase by 1.6 mm. the dielectric constant of the plate, is
A) 5
B) 1.25
C) 4
D) 2.5
Explanation
(a) Here , $t = 2\ mm,\ x = 1.6\ mm,K = ?$
As potential difference remains the same, capacity must remain the same
$\therefore\ \ \ x = t\left( 1 - \frac{1}{K} \right)$
$1.6 = 2\left( 1 - \frac{1}{K} \right),\ \ $which gives $K = 5$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.