Board-style MCQs and past-paper numericals in the BIEK / Sindh Board pattern. Tap an option to check yourself instantly. Solved questions are at the bottom.
Multiple-choice questions
Solved numericals (past papers)
Capacitance from charge and voltage
A capacitor stores a charge of 60 μC when connected to a 12 V supply. Find its capacitance.
C = Q / V = 60×10⁻⁶ / 12
C = 5 × 10⁻⁶ F = 5 μF
Parallel-plate capacitor from geometry
A parallel-plate capacitor has plates of area 0.02 m² separated by 1 mm of air (ε₀ = 8.85×10⁻¹² F/m). Find C.
C = ε₀A / d = (8.85×10⁻¹² × 0.02) / (1×10⁻³)
C = (1.77×10⁻¹³) / (10⁻³) = 1.77 × 10⁻¹⁰ F = 177 pF
Capacitors in parallel
Three capacitors of 2 μF, 3 μF and 5 μF are connected in parallel. Find the equivalent capacitance.
C = C₁ + C₂ + C₃ = 2 + 3 + 5
C = 10 μF
Capacitors in series
Two capacitors of 6 μF and 3 μF are connected in series. Find the equivalent capacitance.
1/C = 1/6 + 1/3 = 1/6 + 2/6 = 3/6 = 1/2
C = 2 μF
Energy stored in a capacitor
A 4 μF capacitor is charged to 200 V. How much energy is stored?
E = ½CV² = ½ × 4×10⁻⁶ × (200)²
E = ½ × 4×10⁻⁶ × 40000 = 0.08 J (80 mJ)
Charge stored at a given voltage
What charge is stored on a 10 μF capacitor connected across 50 V?
Q = CV = 10×10⁻⁶ × 50
Q = 5 × 10⁻⁴ C = 500 μC