The ratio of equivalent capacitance in series and parallel combinations of two capacitors of capacity 5 F and 20 F will be

4 : 25

The correct answer is Option (2) → 4 : 25

For capacitors $C_1 = 5 \, F$ and $C_2 = 20 \, F$ :

Series combination:

$\frac{1}{C_s} = \frac{1}{C_1} + \frac{1}{C_2} = \frac{1}{5} + \frac{1}{20} = \frac{4 + 1}{20} = \frac{5}{20} = \frac{1}{4}$

$C_s = 4 \, F$

Parallel combination:

$C_p = C_1 + C_2 = 5 + 20 = 25 \, F$

Required ratio:

$\frac{C_s}{C_p} = \frac{4}{25}$