Q. The energy required to charge a parallel plate condenser of plate separation d and plate area of cross-section A such that the uniform electric field between the plates is E, is
A) (1/2)ε₀E²Ad
B) (1/2)ε₀E²/Ad
C) ε₀E²/Ad
D) ε₀E²Ad
Explanation
[Solution from source] Energy = (1/2)CV² with C = ε₀A/d and V = Ed, giving (1/2)(ε₀A/d)(Ed)² = (1/2)ε₀E²Ad, i.e. energy density (1/2)ε₀E² times the volume Ad. ε₀E²Ad misses the factor 1/2, and the forms divided by Ad have the wrong dimensions. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.