Series Combination #8211; In series, charge on each capacitor remains same and is equal to the main charge supplied by the battery. Equivalent capacitance of the combinations is 1/C<sub>eq</sub> = 1/C<sub>1</sub> + 1/C<sub>2</sub> or C<sub>eq</sub> = C<sub>1</sub> C<sub>2</sub>/C<sub>1</sub> + C<sub>2</sub>