A condenser is composed of 21 circular plates placed one after the other. The diameter of each plate is 10 cm. The consecutive plates are separated by 0.2 mm thick mica sheets of dielectric constant 6. If the alternate circular plates are connected, calculate the capacitance of the condenser in `muF`.

Explanation

The condenser is composed of 21 circular plates and alternate plates are connected. So here we get 20 identical capacitors connected in parallel whose capacitance is
`C = (20k in_0 alpha)/(d)`
` = (20xx6xx8.854xx10^(-12)xx pi xx2.5xx10^(-3))/(2xx10^(-4))`
`= 4.17xx^(-8)F= 0.041muF`
`[" Here ", k=6, alpha= pi xx(5)^2 cm^2= pi xx2.5xx10^(-3) m^2, d= 2xx10^(-4) m, in_0 = 8.854xx10^(-12)C^2*N^(-1)*m^2]`