Is There an Electric Field at the Midpoint Between Two Protons?

[milkyway11]

What is the electric field halfway in between two protons separated by a distance of 1mm?

When I first did this problem I simply used the electric field equation to solve which is E=kq/r². However, as I came across another similar problem that states: " a proton and an electron are separated by 1micrometer. is there a point directly between them at which the electric field is zero." I realized that maybe I've been doing this kinda of problem wrong.

My answer now to the first question is there is no electric field since the electric field in x-direction would cancel out and there is no y-direction electric field. And the second problem is that there is no point between the two charges that would have a zero field, because it forms a dipole.

Can someone confirm if my thinking is correct? Also, if my new answers are right, please explain to me why we can't just use the electric field equation even though it still gives u a number?

Thank you!

 

[cepheid]

Can someone confirm if my thinking is correct? Also, if my new answers are right, please explain to me why we can't just use the electric field equation even though it still gives u a number?

Thank you!

Yes, your thinking is correct in both cases. Yes, you CAN just use the equation for the electric field to solve these problems.

Do you mean that you get a non-zero number for the case with two protons? If so, you shouldn't. Hint: remember that electric field is a vector, and that you have to add up the electric fields from each proton in order to get the total field.

 

[milkyway11]

Thank you for your fast reply. I think I get why I got a non zero in the first place, because I only calculated the electric field of one proton and completely ignored the other one!

Yes, your thinking is correct in both cases. Yes, you CAN just use the equation for the electric field to solve these problems.

Do you mean that you get a non-zero number for the case with two protons? If so, you shouldn't. Hint: remember that electric field is a vector, and that you have to add up the electric fields from each proton in order to get the total field.

 

[cepheid]

Thank you for your fast reply. I think I get why I got a non zero in the first place, because I only calculated the electric field of one proton and completely ignored the other one!

Yep, that would do it! Glad to be of help.

 

[rwisz]

Your thinking is correct. In the case of two protons, the electric field halfway between them would be zero because the positive fields from each proton would cancel each other out. This is known as a neutral point. Similarly, in the case of a proton and an electron, the electric field would also be zero at a point directly between them because the opposite charges would cancel each other out.

The reason why we cannot simply use the electric field equation in these cases is because the equation assumes a single point charge, whereas in reality we have two charges interacting with each other. The electric field from one charge is affected by the presence of the other charge, leading to a more complex situation. This is why we need to consider the interactions between the charges and the resulting electric field at different points between them.