TP 20.44

Given: A = 0.0120 m²

d = 0.880 mm = 0.880 x 10^-3 m

k = 2.00

(a) Q = 4.70 mC = 4.70 x 10^-6 C

Find: DV =?

C = Q/DV

DV = Q/C

C = k e_o A / d

DV = Q d/(k e_o A) = (4.70 x 10^-6 C) (0.880 x 10^-3 m ) / ((2.00)(8.85 x 10^-12 C²/(N-m²))(0.0120 m²)) = 19,500 V

(b) Since the potential difference across the plates is inversely proportional to the dielectric constant, as the dielectric constant increases, the potential difference will decrease.

(c) Since the dielectric constant is increased by a factor of two, the potential difference will decrease by a factor of two:

DV = 9,750 V