JEE Main202522 Jan 2025Morning ShiftPhysicsCapacitanceActual
A parallel-plate capacitor of capacitance 40 ~F is connected to a 100 V power supply. Now the intermediate space between the plates is filled with a dielectric material of dielectric constant K =2 . Due to the introduction of dielectric material, the extra charge and the change in the electrostatic energy in the capacitor, respectively, are
Options
- A4 mC and 0.2 J
- B8 mC and 2.0 J
- C2 mC and 0.4 J
- D2 mC and 0.2 J
Correct answer
A. 4 mC and 0.2 J
Step-by-step solution
aligned & q =( KC - C ) V & =40 10⁻⁶ 100 & =4000 10⁻³=4 mC & U = 1 2 C ^ V ^2- 1 2 CV ^2= 1 2 ( ~K -1) CV ^2 & = 1 2 CV ^2(2-1) & = 1 2 CV ^2= 1 2 40 10⁻⁶ 10000 & =0.2 ~J aligned