Question

Two identical parallel plate capacitors are
connected in series and then joined with a battery
of 100 V. A sheet of dielectric constant 4.0 is
inserted between the plates of second capacitor.
The potential difference across the capacitors will
be respectively :
(1) 50 V, 50 V (2) 80 V, 20 V
(3) 20 V, 80 V (4) 75 V, 25 V​

Answer 1

Answer : As we learnt in

Series Grouping -

\frac{1}{C_{eq}}=\frac{1}{C_{1}}+\frac{1}{C_{2}}+\cdots

- wherein

q=\left ( C_{eq} \right )50 = \frac{4C\times C}{4C+C}.50 = 40C

\Rightarrow V_{1} = \frac{40C}{C} = 40 \ V

\Rightarrow V_{2} =\frac{40C}{4C} = 10 \ V

Option 1)

50V, 50V

This option is incorrect

Option 2)

40V, 10V

This option is correct

Option 3)

10V, 40V

This option is incorrect

Option 4)

None of these

This option is incorrect