An electron as q = 1.602 * 10-19 C is placed .03m away from spherical object with a net charge of -7.2 C. A. What is the force exerted on the electron?
B. How strong is the electric field at the electron’s location?
C. How much work would be done on the electron if it was moved so that it’s .001m away from the sphere?
D. Now replace the electron with a positron (q = +1.602 × 10-19C). Explain.

See explanation

Explanation:

The electric force exerted on the electron is given by Coulomb's law;

F= KqQ/r^2

F= force on the electron

K= constant of Coulomb's law

q= charge on the electron

Q=charge on the spherical object

r= distance between the charges

F= 9×10^9 × -1.602 × 10^-19 × (-7.2)/(0.03)^2

F= 103.8 × 10^-10/9×10^-4

F= 11.53 ×10^-6

F= 1.153 ×10^-5 N

The force in this case is repulsive

E= F/q

E= 1.153 ×10^-5 N/ 1.602 * 10-19 C

E= 0.719 × 10^14

E= 7.19 × 10^13 NC-1

The electro field around the electron is very strong.

c)

V= Kq/r

V= 9×10^9 × 1.602 × 10^-19/0.001

V= 14418 × 10^-10

V=1.4418 ×10^-6 V

W= qV

W= 1.602×10^-19 C × 1.4418 ×10^-6 V

W= 2.31 ×10^-25 J

Replacing the electron with a positron

F= 9×10^9 × 1.602 × 10^-19 × (-7.2)/(0.03)^2

F= 103.8 × 10^-10/9×10^-4

F= 11.53 ×10^-6

F= -1.153 ×10^-5 N

The force in this case is attractive