Coulomb's Law (Electric Force) Video Lessons

Concept

# Problem: A point charge q1 = -2.1 μC is located at the origin of a co-ordinate system. Another point charge q2 = 6.7 μC is located along the x-axis at a distance x2 = 6.7 cm from q1.1. What is F12,x, the value of the x-component of the force that q1 exerts on q2?2. Charge q2 is now displaced a distance y2 = 2.8 cm in the positive y-direction. What is the new value for the x-component of the force that q1 exerts on q2?3. A third point charge q3 is now positioned halfway between q1 and q2. The net force on q2 now has a magnitude of F2,net = 8.005 N, and points away from q1 and q3. What is the value (sign and magnitude) of the charge q3?

###### FREE Expert Solution

In this problem, we're going to use Coulomb's law:

$\overline{){\mathbf{F}}{\mathbf{=}}\frac{\mathbf{k}{\mathbf{q}}_{\mathbf{1}}{\mathbf{q}}_{\mathbf{2}}}{{\mathbf{r}}^{\mathbf{2}}}}$, where F is electric force, k is Coulomb's constant, and r is the separation between charges q1 and q2.

1.

The value of force that q1 exerts on q2 can be given by Coulomb's law as:

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###### Problem Details

A point charge q1 = -2.1 μC is located at the origin of a co-ordinate system. Another point charge q2 = 6.7 μC is located along the x-axis at a distance x2 = 6.7 cm from q1.
1. What is F12,x, the value of the x-component of the force that q1 exerts on q2?

2. Charge q2 is now displaced a distance y2 = 2.8 cm in the positive y-direction. What is the new value for the x-component of the force that q1 exerts on q2?

3. A third point charge q3 is now positioned halfway between q1 and q2. The net force on q2 now has a magnitude of F2,net = 8.005 N, and points away from q1 and q3. What is the value (sign and magnitude) of the charge q3?