If a 10μF capacitor is to have an energy content of 20J, it must be placed across a potential difference of:
Correct answer: B. 2000 volts
- A. 4 volts
- B. 2000 volts
- C. 9 volts
- D. 1 volt
Explanation
Using the energy formula U = (1/2)CV², we rearrange to solve for V: V = √(2U/C). V = √(2 × 20 J / 10 × 10⁻⁶ F) = √(40 / 10⁻⁵) = √4 × 10⁶ = 2000 V.
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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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