In the image below, on which charge can the field be zero? Thank you!

enter image source here

Also why? I'm curious! Thank you :)

2 Answers
Sep 24, 2017

I think none of them...

Explanation:

Not knowing the context of the question makes it tricky to be certain, but any charge in the presence of another charge will be subject to an electrical field.

Good luck.

Sep 25, 2017

None of them.

Explanation:

Let's number the positive charge number 1 and assign number 3 to the charge at the corner opposite number 1. Charge 1 would attract charge 3 because opposite charges attract.

If the value of the charges 2 and 4 are equal, they would repel charge 3 in a direction along the diagonal that passes through charge 1 and charge 3. That repulsion would be a force away from charge 1.

Depending on the values of charge 1 and charges 2 and 4, these forces of attraction and repulsion could have equal magnitude and therefore cancel. The result of that would be that the force on charge 3 is zero.

If that condition exists, would the field at the location of charge 3 very close to charge 3) be zero? No. I assume the question is asking about field at a location very close to charge 3. Charge 3 itself would be giving off a field.

The closer to an isolated charge the field evaluation is, the higher the field will be. The same would be true of a field evaluation near charge 3.

I started my thoughts about this question concentrating of the forces of attraction and repulsion. I saw that the force on charge 3 could be zero. But then I realized that did not mean that the field near charge 3 could be zero.

I will take the question as written and agree with Mark C. None of them.

I hope this helps,
Steve