Question

A set of charged plates have anarea of 5.10*10^-3 m^2 andseparation 1.42*10^-5 m. Howmuch charge must be placed onthe plates to create a potentialdifference of 125 V across them?(The answer is *10^-7 C. Just fill inthe number, not the power.)

Answer 1

Given data:

Area of plates:

`A=5.10*10^(-3)\text{ m}^2`

Separation between the plates:

`d=1.42*10^(-5)\text{ m}`

Potential difference:

`V=125\text{ V}`

The capacitance of the capacitor is given as,

`C=(A\epsilon_(\circ))/(d)`

Here, ε_o is the permittivity of the free space.

Substituting all known values,

`\begin{gathered} C=(5.10*10^(-3)*8.85*10^(-12))/(1.42*10^(-5)) \\ =3.178*10^(-9)\text{ F} \end{gathered}`

The charge on the capacitor is given as,

`Q=CV`

Substituting all known values,

`\begin{gathered} Q=3.178*10^(-9)*125 \\ =3.9725*10^(-7)\text{ C} \end{gathered}`

Therefore, the charge on the plates is 3.9725×10^-7 C.