JEE Advanced2008PhysicsCapacitanceActual
A parallel plate capacitor C with plates of unit area and separation d is filled with a liquid of dielectric constant K=2 . The level of liquid is d 3 initially. Suppose the liquid level decreases at a constant speed v , the time constant as a function of time t is
Options
- A6 ₀ R 5 d+3 v t
- B(15 d+9 v t) ₀ R 2 d^2-3 d v t-9 v^2 t^2
- C6 ₀ R 5 d-3 v t
- D(15 d-9 v t) ₀ R 2 d^2+3 d v t-9 v^2 t^2
Correct answer
A. 6 ₀ R 5 d+3 v t
Step-by-step solution
After time t , thickness of liquid will remain ( d 3 -v t ) . Now, time constant as function of time aligned _c & =C R & .= ₀(1) R (d- d 3 +v t )+ d / 3-v t 2 Applying C= ₀ A d-t+ t k ) & = 6 ₀ R 5 d+3 v t aligned correct option is (a).