The work done in placing a charge of 8μC on a condenser of capacity 100 nF is:
Correct answer: C. 3.2 x 10⁻⁴ J
- A. 16 x 10⁻⁵ J
- B. 32 x 10⁻⁶ J
- C. 3.2 x 10⁻⁴ J
- D. 16 x 10⁻⁴ J
Explanation
The work done to charge a capacitor is equal to the energy stored, U = Q²/(2C). U = (8 × 10⁻⁶ C)² / (2 × 100 × 10⁻⁹ F) = (64 × 10⁻¹²) / (200 × 10⁻⁹) = 0.32 × 10⁻³ J = 3.2 × 10⁻⁴ J.
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Electrostatics describes forces between charges through Coulomb's law, electric fields and field intensity, then uses electric potential to measure energy per unit charge. Capacitors store charge and electrical energy, with capacitance depending on geometry and dielectric material, not simply on the amount of charge present.
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