A capacitor made of two circular plates each of radius 12 cm and separated by 5 cm. The capacitor is being charged by an external source. The charging current is constant and equal to 0.15 A. The capacitance of the parallel plate capacitor is

Options

A. 40 pF
B. 45 pF
C. 70 pF
D. 80 pF

Answer

D

Explanation

Here, R = 12 cm = 0.12 m
d = 5 mm = `5xx10^(-3)m, epsilon_(0)=8.85xx10^(-12)C^(2)N^(-1)m^(-2)`
Also, `A=piR^(2)=3.14xx(0.12)^(2)m^(2)=4.5xx10^(-2)m^(2)`
`"Capacitance, C"=(epsilon_(0)A)/(d)=(8.85xx10^(-12)xx4.5xx10^(-2))/(5xx10^(-3))`
`=79.65xx10^(-12)=80pF`