You are asked to construct a capacitor having a capacitance near 1 nF and a brea

Question

You are asked to construct a capacitor having a capacitance near 1 nF and a breakdown potential in excess of 11000 V. You think of using the sides of a tall plastic drinking glass as a dielectric (with a dielectric constant 6.7 and dielectric strength 11 kV/mm), lining the inside and outside curved surfaces with aluminum foil to act as the plates. The glass is 17 cm tall with an inner radius of 3.81 cm and an outer radius of 4.14 cm. (a) What are the capacitance and (b) breakdown potential of this capacitor?

Explanation / Answer

here,

a)

The capacitance of a cylindrical capacitor with a dielectric = *2*pi*e0*L/ln(rb/ra)

where is the dielectric constant = 6.7

so

C = 6.7 * 2 * pi * 8.85 * 10^-12 * 0.17 / ln(4.14/3.81)

C = 7.62 * 10^-10F = 0.762 nF

B)

For the Dielectric strength = 1.1 * 10^7V/m

so V = 1.1 * 10^7 * 0.4 * 10^-2 m = 44000 V

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.