Answer: E = 1.93×10^-7 J
Explanation: The formulae for getting the energy stored in a capacitor is given as
E =Cv²/2
Where E = energy stored in capacitor (joules), C = capacitance of capacitor (farad), v = applied voltage =150v.
The formulae implies that we need to get the capacitance of the capacitor (C) first before we can get the energy.
From the parameters given to us
Area of plates =A = 87.5cm² = 87.5/10000 = 0.00875m²
Distance between plates = d = 4.50mm = 4.50/1000 = 0.0045m
C = ε0A/d
Where ε0 = permittivity of free space = 8.85×10^-12 F/m
C = 8.85×10^-12 × 0.00875/ 0.0045
C = 7.743×10^-14/0.0045
C = 1.72×10^-11 F.
Recall that E = Cv²/2
E = ( 1.72×10^-11 × 150×150) /2
E = 3.87×10^-7/2
E = 1.93×10^-7 J
