# Finding the charge of a particle

1. Jan 20, 2009

### keishuu

1. The problem statement, all variables and given/known data

Two charged particles A and B are along in the Universe, 8 cm apart. The charge of A is 40 nC. The net electric field at one certain point 4 cm from A is zero. What can you conclude about the charge of B. Choose every correct answer. (a) it can be 40 nC. (b) it can be 120 nC. (c) It can be 360 nC (d) It can be -40 nC (e) It can be -120 nC (f) It can be -360 nC (g) It can have any of an infinite number of values (h) It can have any of several values (i) it must have one of three values (j) it must have one of two values (k) it must have one certain value (l) no possible value for the charge of b exists; the situation is impossible

2. Relevant equations

Coloumb's law

3. The attempt at a solution
Using coloumb's law and setting the point 4 cm to the left and right of A, I figured that B could have a charge of -40 nC or -360nC. However, I'm not too sure if it could have another value such as the -120 nC suggested in the problem. Is this possible? Thanks for taking the time to read this.