Coulombs Law

The force between two charges is given by Coulomb's law:

F%20%3D%20k%20%5Cfrac%7B%7Cq_1%20q_2%7C%7D%7Br%5E2%7D

where

k

is Coulomb's constant,

q_1

and

q_2

are the charges, and

r

is the distance between them. After adding

%2B2%20%5C%2C%20%5Cmu%20C

to both spheres, the new charges are:

q_1%20%3D%20%2B7%20%5C%2C%20%5Cmu%20C%20%2B%202%20%5C%2C%20%5Cmu%20C%20%3D%20%2B9%20%5C%2C%20%5Cmu%20C%2C%20%5Cquad%20q_2%20%3D%20-5%20%5C%2C%20%5Cmu%20C%20%2B%202%20%5C%2C%20%5Cmu%20C%20%3D%20-3%20%5C%2C%20%5Cmu%20C

Thus, the new force

F'

is:

F'%20%3D%20k%20%5Cfrac%7B%7C9%20%5C%2C%20%5Cmu%20C%20%5Ctimes%20(-3)%20%5C%2C%20%5Cmu%20C%7C%7D%7Br%5E2%7D%20%3D%202F

Thus, the new force is

2F

Chapter Questions
1 MCQs