1. The force between a pair of charges is 100 newtons. The distance between the charges is 0.01 meter. If one of the charges is 2 u 10-10 C, what is the strength of the other charge?

2. The force between two charges is 2 newtons. The distance between the charges is 2 u 10-4 m. If one of the charges is 3 u 10-6 C, what is the strength of the other charge?

1.

2.

Explanation:

1. Electrostatic force is given as:

where k = Coulombs constant

q = charge of first charge

Q = charge of the second charge

r = distance between them

From the question:

F = 100 N

q  =

r = 0.01 m

We need to find Q.

From the formula of force, we have that Q is:

This is the charge, Q, of the second charge.

2. From the question:

F = 2 N

q  =

r =

We need to find Q.

Using the same formula for Q as in 1. above, we have that:

This is the charge, Q, of the second charge.

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