Question

If the electric field inside a capacitor exceeds the dielectric strength of the dielectric between its plates, the dielectric will break down, discharging and ruining the capacitor. Thus, the dielectric strength is the maximum magnitude that the electric field can have without breakdown occurring. The dielectric strength of air is 3.0 106 V/m, and that of neoprene rubber is 1.2 107 V/m. A certain air-gap, parallel plate capacitor can store no more than 0.076 J of electrical energy before breaking down. How much energy can this capacitor store without breaking down after the gap between its plates is filled with neoprene rubber? J

Answer 1

Answer:

0.304 J

Explanation:

Energy stored in a capacitor W = 1/2QV  where Q = charge and V = voltage applied. Also, V = Ed where E = dielectric strength and d = distance between plates.

The initial energy stored with air dielectric W₀ = 0.076 J and E₀ = 3.0 × 10⁶ V/m

W₀ = 1/2QV = 1/2QE₀d

Q = 2W₀/E₀d

For the neoprene dielectric, energy stored is

W₁ = 1/2QE₁d = 1/2 × (2W₀/E₀d) × E₁d = W₀E₁/E₀ where E₁ = dielectric strength of neoprene rubber = 1.2 × 10⁷ V/m

W₁ = W₀E₁/E₀ = 0.076 J × 1.2 × 10⁷ V/m ÷ 3.0 × 10⁶ V/m = 0.304 J

Answer 2

Answer:

The max. Energy that can be stored in the neoprene rubber capacitor will be 0.304J

Explanation:

Detailed explanation and calculation is shown in the image below