For a parallel plate capacitor, the energy density is _.
Correct answer: B. ½ εrεo E2
- A. ½ εrεo E
- B. ½ εrεo E2
- C. εrεo E
- D. εrεo E2
Explanation
Energy density is generally given as ½ εo E2. However, if the medium is different from free space, the permittivity of free space εo will be multiplied by the relative permittivity of the medium εr Hence now, the energy density of the capacitor can be written as ½ εoεr E2. Hence, Option B is correct.
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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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