Which property of a dielectric material describes its ability to store electrical energy in an electric field?

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Multiple Choice

Which property of a dielectric material describes its ability to store electrical energy in an electric field?

Dielectric constant, or relative permittivity, describes how much electric energy a dielectric can store when placed in an electric field. When a dielectric is in a field, its molecules polarize, increasing the capacitor’s ability to store charge for a given voltage. For a capacitor with area A and gap d, the capacitance is C = ε A / d, where ε = ε0 ε_r. A higher dielectric constant (ε_r) increases C and thus the energy stored, since the energy is (1/2) C V^2. Equivalently, the energy density in the field is u = 1/2 ε E^2, tying storage directly to ε. Insertion loss, common mode current, and EMI describe other phenomena (signal loss, unwanted currents, and interference) and do not capture the dielectric’s energy-storage capability.

Dielectric constant, or relative permittivity, describes how much electric energy a dielectric can store when placed in an electric field. When a dielectric is in a field, its molecules polarize, increasing the capacitor’s ability to store charge for a given voltage. For a capacitor with area A and gap d, the capacitance is C = ε A / d, where ε = ε0 ε_r. A higher dielectric constant (ε_r) increases C and thus the energy stored, since the energy is (1/2) C V^2. Equivalently, the energy density in the field is u = 1/2 ε E^2, tying storage directly to ε. Insertion loss, common mode current, and EMI describe other phenomena (signal loss, unwanted currents, and interference) and do not capture the dielectric’s energy-storage capability.

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