The ratio of equivalent capacitance in series and parallel combinations of two capacitors of capacity 5 F and 20 F will be
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 4 : 25
In series the reciprocals of the capacitances add, and in parallel the capacitances add.
\( \displaystyle C_{\mathrm{s}} = \frac{C_1 C_2}{C_1 + C_2} = \frac{5 \times 20}{5 + 20}\,\mathrm{F} = 4\,\mathrm{F} \)
\( C_{\mathrm{p}} = C_1 + C_2 = 5 + 20 = 25\,\mathrm{F} \)
\( \displaystyle \frac{C_{\mathrm{s}}}{C_{\mathrm{p}}} = \frac{4}{25} = 4 : 25 \)