CBSE 2026 · Region 3 · Set 1 · Q29 · 4 marks

Capacitors are manufactured with certain standard capacitances and working voltages. However, these standard values may not be the ones that are actually needed in a particular application. Two or more capacitors can be grouped in series or in parallel to achieve desired capacitance and voltage. When connected in series, the total capacitance decreases while the voltage rating increases, whereas in parallel connections, the total capacitance increases and maintains the same voltage rating. A capacitor stores energy in the electric field between its plates and stored energy is proportional to the square of the voltage and capacitance $\displaystyle \mathrm{U}=\frac{1}{2} \mathrm{CV}^{2}$, where symbols have their usual meanings.

Two capacitors, one of $\displaystyle 3 \mu \mathrm{~F}$ and the other of $\displaystyle 6 \mu \mathrm{~F}$, are connected in series in the circuit as shown in the figure, for a long time.

(i)

The total capacitance of the circuit is :

(A)

$\displaystyle 6 \mu \mathrm{~F}$

(B)

$\displaystyle 3 \mu \mathrm{~F}$

(C)

$\displaystyle 9 \mu \mathrm{~F}$

(D)

$\displaystyle 2 \mu \mathrm{~F}$

(ii)

The current in the $\displaystyle 10 \Omega$ resistor is :

(A)

$\displaystyle 0 \cdot 3 \mathrm{~A}$

(B)

0.$\displaystyle 6$ A

(C)

$\displaystyle 0 \cdot 2 \mathrm{~A}$

(D)

$\displaystyle 0$ (iii) The potential difference between point A and B is :

(A)

$\displaystyle 2$ V

(B)

0.$\displaystyle 3$ V

(C)

$\displaystyle 0 \cdot 2 \mathrm{~V}$

(D)

$\displaystyle 3$ V

(iv)

(a)OR(b)

The value of charge on the plates of the $\displaystyle 6 \mu \mathrm{~F}$ capacitor is :

(A)

$\displaystyle 6 \mu \mathrm{C}$

(B)

$\displaystyle 4 \mu \mathrm{C}$

(C)

$\displaystyle 12 \mu \mathrm{C}$

(D)

$\displaystyle 8 \mu \mathrm{C}$

CBSE Class 12 Physics past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.