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help please A commercial capacitor is to be constructed as shown in the figure b

ID: 1534083 • Letter: H

Question

help please

A commercial capacitor is to be constructed as shown in the figure below. This particular capacitor is made from two strips of aluminum foil separated by a strip of paraffin-coated paper. Each strip of foil and paper is 7.20 cm wide. The foil is 0.004 50 mm thick, and the paper is 0.020 0 mm thick and has a dielectric constant of 3.70. What length should the strips have if a capacitance of 9.50 times 10^-8 F is desired before the capacitor is rolled up? (Adding a second strip of paper and rolling the capacitor would effectively double its capacitance by allowing charge storage on both sides of each strip of foil.)

Explanation / Answer

we know that,

capacitance C = k*e0*A / d

A = C*d / k*e0

where d = thickness of paper = 0.02 mm

k = 3.7

C = 9.5*10^(-8) F

A = (9.5*10^(-8)*0.02*10^(-3) / (3.7*8.85*10^(-12)

A = 0.058 m^2

length l = A / w

l = 0.058 / 0.072

l = 0.805 m