A dielectric slab with constant is slowly inserted between the plates of a…
PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A dielectric slab with constant κ>1 is slowly inserted between the plates of a parallel-plate capacitor that remains connected to an ideal battery. Which of the following best describes the energy transfers and work involved during the insertion?
(a) The external agent must supply positive work, increasing the capacitor’s energy, while the battery absorbs an equal amount of energy.
(b) Neither the battery nor the external agent does work because the potential difference is fixed; the capacitor’s stored energy is unchanged.
(c) The battery supplies energy to the circuit, increasing the capacitor’s stored energy, while the external agent does negative work during the insertion.
(d) Both the battery and the external agent supply positive work, so the energy stored in the capacitor more than doubles.