How do I find the points where the electric field is zero?

[Mason Smith]

Homework Statement

Two pairs of charges are shown in Figure 1.

Homework Equations

The Attempt at a Solution

I originally thought that the electric field past point 7 (i.e. points 8,9, 10) was the solution. However, this is wrong. I then considered point 1, yet that was wrong too. I even considered that there was no point at which the electric field is zero. However, none of these guesses seem to be right. Where am I going wrong in my thinking?

 

[berkeman]

Homework Statement

Two pairs of charges are shown in Figure 1. View attachment 112822

Homework Equations

The Attempt at a Solution

I originally thought that the electric field past point 7 (i.e. points 8,9, 10) was the solution. However, this is wrong. I then considered point 1, yet that was wrong too. I even considered that there was no point at which the electric field is zero. However, none of these guesses seem to be right. Where am I going wrong in my thinking?

Welcome to the PF.

What are the magnitudes and signs of the 4 charges shown?

 

[Mason Smith]

Welcome to the PF.

What are the magnitudes and signs of the 4 charges shown?

MasteringPhysics labeled this question as a conceptual question, so no magnitude was given for the charges.

 

[berkeman]

MasteringPhysics labeled this question as a conceptual question, so no magnitude was given for the charges.

Actually, now that I zoom into the figure, I see the left-hand charges are +4 and the right charge in (a) is +1 and in (b) is -1.

So I would write Gauss' law for the charge configuration to see where the E-fields from the + and - charges got closest to zero (I agree it will be to the right of the right-hand-charge in (b)...