Science Forums 2

[sebbysteiny]

1) this is a three stage process.

Stage 1. Calculate the force on the charge from one of the charges.
F1= q1q2/r^2 4*pi*E0 q1 = +3.8x10^-6 C, q2 = + 2.3x10^-6 C r = .2 + .1 = .3

F1 = 0.873N

Stage 2. Calculate the force on the charge from the other charge.

F2 = q3q2/r^2 4*pi* E0 q3 = -2.0x10^-6 C, q2 = + 2.3x10^-6 C, r = .1

F2 = -4.13N (ie to the left).

Stage 3. Calcultate the resulting force

F = F1 + F2 = -3.26N (ie to the left).

That's how to work it out.

However, I notice I have got the wrong answer. That is because I did not draw the charge picture correctly. This is partly because I don't have a clue what the question means by '0.1m to the right of the second charge' and partly because I didn't read it properly.

Nevertheless, the simple easy method works.

If the question were in 3 dimensions, it would still work. You just add the Force vectors together.