Test: Capacitors and Capacitance (3 Nov) - JEE MCQ

In a parallel plate capacitor the capacity of capacitor.

The capacity of capacitor increases if area of the plate is increased.

Definition based

Q = CV

When key K is kept closed, condenser C is charged to potential V. When plates of capacitors are moved apart, its capacitance, C = ϵ_oA/d decreases.
As potential of condenser remains same, charge Q = CV decreases. So option is correct. Once key K is closed, condenser gets charged, Q = CV.
Now, if key K is opened, battery is disconnected, no more charging can occur i.e. Q remains same.
As plates or capacitor are moved apart, its capacity C = ϵ_oA/d decreases.
Therefore, its potential, V = q/C increases

Q = CV, where C is decided only by the geometrical factors

Correct answer is A.

W = Energy stored in the capacitor

Capacitance of an isolated spherical conductor =4π€R , where €=permittivity of vacuum
C=2×10^-6F
C=4π€R
4×3.14×8.85×10^-12×R=2×10^-6
R=2×10^-6/4×3.14×8.85×10^-12
=1.8×10⁴ m

Alcohol and HCl are polar molecules since they have a net dipole moment towards a particular direction. Both water and benzene are non-polar molecules. But water is a conductor of electricity, whereas benzene is a dielectric (insulator).

Mica capacitors are preferred for high frequency circuits because they have low ohmic losses and less reactance.