Answer to Question #329534 in Electricity and Magnetism for Terdo

Question

A parallel-plate air capacitor is to store charge of magnitude 240.0 pC on each plate when the

potential difference between the plates is 42.0 V. (a) If the area of each plate is 6.80 cm2

, what is

the separation between the plates? (b) If the separation between the two plates is double the value

calculated in part (a), what potential difference is required for the capacitor to store charge of

magnitude 240.0 pC on each plate?

Answer 1

$C=\frac qU=\frac{\varepsilon_0 S}d,$

a)

$d=\frac{\varepsilon_0 SU }{q}=1.05~mm,$

b)

$U'=2U=84~V.$