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A capacitor is constructed of two concentric spherical metal shells. The inner s

ID: 1595180 • Letter: A

Question

A capacitor is constructed of two concentric spherical metal shells. The inner shell has a radius R_1 = 15.0 cm, and the outer cylinder has a radius R_2 = 16.0 cm. The hollow space between the two shells is filled with nylon having a dielectric constant of 4.0. A charge of Q = 1mu C is transferred from the inner shell to the outer shell. (a) Find the field between the two using Gauss's law. (b) What is the voltage difference delta V between the inner and outer shells? (c) What is the capacitance C = Q/AV of this spherical capacitor (in pF)?

Explanation / Answer


Given; R1 = 0.15 m, R2 = 0.16 m

(a)electric field E = - K*Q/R^2

E1 = - 9.0*10^9*1*10^-6/0.15^2

= -400 K.N/C

E2 = - 9.0*10^9*1*10^-6/0.16^2

= -351.56 K.N/C

(b) The voltage diffrence between the inner and outer shells

delta V = (Q/4*pi*E0)*(1/R2-1/R1)

= 1*10^-6*9*10^9*(1/0.16-1/0.15)

= -3.75*10^3 volts

(c) The capacitance is

C = Q/delta V

= 1*10^-6/3.75*10^3

= -0.267*10^-9 F