Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert

A parallel plate capacitor has plates of area A separated by distance d between them. It is filled with a dielectric which has a dielectric constant that varies as Kx=K01+αx where x is the distance measured from one of the plates. If αd<<1, the total capacitance of the system is best given by the expression:
PhysicsCapacitanceJEE MainJEE Main 2020 (07 Jan Shift 1)
Options:
  • A AK0ε0d1+αd2
  • B AK0ε0d1+αd22
  • C AK0ε0d1+α2d22
  • D AK0ε0d1+αd
Solution:
1671 Upvotes Verified Answer
The correct answer is: AK0ε0d1+αd2
Capacitance of element, dC=K01+αxε0Adx
1dC=0ddxK0ε0A1+αx
1C=1K0ε0Aαln1+αd
Given αd1
1C=1K0ε0Aααd-α2d22
1C=dK0ε0A1-αd2
C=K0ε0Ad1+αd2

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.