Question

Two large parallel metal plates
(3.00 mm apart) are charged to a
potential difference, of 12V. They
are now disconnected from the
battery and pulled apart to 5,00
mm. What is the new potential
difference between plates ?
10V
20V
30V
15V​

Answer 1

Answer:

10v...........................................

Answer 2

The correct answer is 20V.

Given,

Distance between two parallel metals plates, d = 3mm

                                                                               = 3 x $10^{-3}$m

potential difference, V= 12V

Distance between two parallel metal plates after they have been disconnected from the battery, d' = 5mm

                                                        = 5 x $10^{-3}$ m

To Find,

the new potential difference between plates.

Solution,

E = $\frac{V}{d} = \frac{12}{3 X 10^{-3} }$ = 4 x $10^{3}$ V/m

After disconnecting from the battery the new potential difference would be,

V' = E x d' = 4 x $10^{3}$ x 5 x $10^{-3}$ = 20V

∴ Hence the new potential difference between plates is 20V.