A parallel-plate capacitor with plate area and plate separation is connected to a battery

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

A parallel-plate capacitor with plate area 0.020 m20.020\,\text{m}^2 and plate separation 1.0 mm1.0\,\text{mm} is connected to a 24 V24\,\text{V} battery. After the connection is made, a dielectric with κ=5\kappa = 5 completely fills the gap while the battery remains attached. What is the energy density (energy per unit volume) stored in the dielectric after it is inserted? (a) 3.2×10−1 J m−33.2\times10^{-1}\,\text{J}\,\text{m}^{-3} (b) 2.5×10−3 J m−32.5\times10^{-3}\,\text{J}\,\text{m}^{-3} (c) 1.3×10−2 J m−31.3\times10^{-2}\,\text{J}\,\text{m}^{-3} (d) 6.4×10−2 J m−36.4\times10^{-2}\,\text{J}\,\text{m}^{-3}

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