Question

A test charge of +2 µC is placed halfway between a charge of +6 µC and another of +4 µC separated by 10 cm.

a. What is the magnitude of the force on the test charge?

I know the answer and how to get it. 14.4 N

b. What is the direction of this force (away from or toward the +6 µC charge)?

**I understand everything about this question except part B** any drawings or explanations would be greatly appreciated.

Answer 1

here,

q1 = 6 uC = 6 * 10^-6 C

q2 = 4 uC = 4 * 10^-6 C

q3 = 2 uC = 2 * 10^-6 C

r = 10 cm = 0.1 m

a)

the magnitude of force on test charge placed between them , F = K * q1 * q3 /(r/2)^2 - K * q2 * q3 /(r/2)^2

F = 9 * 10^9 * 2 * 10^-6 * 10^-6 /(0.1/2)^2 * (6- 4 ) N

F = 14.4 N

b)

as all the charges are positive

the electric feild due to positive charge is away from the charge

so, both charges repels the test charge

as the magnitude of 6 uc is greater than 4 uC

the direction of force on the test charge is away from the 6 uC charge