A `10.0muF` parallel-plate capacitor with circular plates is connected to a `12.0 V` battery.
(a) What is the charge on each plate?
(b) How much charge would be on the plates if their separation were doubled while the capacitor remained connected to the battery?
(c) How much charge would be on the plates if the capacitor were connected to the `12.0 V` batter `Y` after the radius of each plate was doubled without changing their separation?

Answer

C, D

Explanation

a. `q=CV`
b. `C=(epsilon_0A)/d` or `Cprop1/d`
if d is doubled, `C` will remain half. Hence `q` will also remain half.
`c.q=CV=((epsilon_0A)/d)V=(epsilon_0(piR^3)V)/d`
`orqpropR^2`
`R` is doubled. Hence q will become four times or `480 muC`