Question

5 and 6 help

A parallel plates capacitor with air between its plates is charged by connecting it to a 4 V battery until it is fully charged and a charge 0-12x10'C is stored on the plates of the capacitor. The electrostatic potential energy that stored in this capacitor is Select one: a. 15 x 10 b. 10x10') O c.24x10 d. 1,8 x 10% e 6.0 x 10 A uniformly charged rod of length 10 and charge Q-10 C is lying on the x axis so that its center is at the origin of the xx ans. The electric potential that this charged rod creates at a point A on the x axis with coordinates A 25 cm.) is Select one: a. 261x 10' b. 1.50 x 10' OC 3.65 x 10 v O d. 3.50 KV e. 2.80 eV Next page

Answer 1

5)

Energy stored in capacitor , U = 1/2 * Q * V

U = 1/2 * 12e-6 * 4

U = 2.4e-5 J

option (c )

____________

6)

Electric potential at a point in line with a charged rod at a distance 'r' is given as

V = (kQ / L) ln ( r + L / r)

notice that rod is centered at origin, so point x = 25 cm is actually 20 cm from right en means r = 20 cm

V = ( 9e9 * 10 / 0.1 ) ln ( 0.20 + 0.1 / 0.20)

V = 3.65e5 V

option (c) is fine