Electrostatics Question 264
Question: A dielectric slab of thickness is inserted in a parallel plate capacitor whose negative plate is at and positive plate is at . The slab is equidistant from the plates. The capacitor is given some charge. As one goes from 0 to [IIT-JEE 1998]
Options:
A) r
B) 2r
C) r/2
D) r/4
Show Answer
Answer:
Correct Answer: D
Solution:
Charge q will momentarily come to rest at a distance r from charge Q when all it’s kinetic energy converted to potential energy i.e.
Therefore the distance of closest approach is given by
therefore
Hence if v is doubled, r becomes one fourth.