# Find electric force on a point charge

The answers are given, but no workings.

*I only need solutions for these *

1. What is the magnitude of the force on a change of +2 x 10-7C that is 0.3m from a charge of -5 x 10-7C?

Answer: 10-2N attractive force.

2. Two electrons repel each other with a force of 10-8N. How far apart are they?

Answer: 1.5 x 10-10m

3. A test charge of +2 x 10-7C is located 5cm to the right of a charge of +1 x 10-6C and 10cm to the left of a charge of -1 x 10-6C. The three charges lie on a straight line. Find the force on the test charge.

Answer: 0.9 to the right

4. Three +100-statC charges are arranged in a straight line, the second charge (B) is 20cm to the right of the first (A) and the third (C) is 50cm to the right of A. What is the force exerted by charges A and B on C?

Answer: 15.1 dyu

#### Solution Preview

Please refer to the attached files.

*I only need solutions for these *

1. What is the magnitude of the force on a change of +2 x 10-7C that is 0.3m from a charge of -5 x 10-7C?

Answer: 10-2N attractive force.

Solution:

The electric force of a point charge as a result of the presence of another point charge is defined by the following equation:

F=(kq_1 q_2)/r^2

=(9.0×〖10〗^9 N m^2 C^(-2)×2×〖10〗^(-7) C×5×〖10〗^(-7) C)/〖(0.3m)〗^2

=〖10〗^(-2) N

Because the two point charges are of opposite charges, the force between them is attractive. Therefore, there is a 10-2 N attractive force on the +2×10-7C point charge.

2. Two electrons repel each other with a force of ...

#### Solution Summary

Four questions regarding the Coulomb's law are answered. In all question, a point charge is placed together with one (or two) other point charges in a straight line. The resulting electric force is found.