Hi,

Can you help with the following (please refer to attached). If I understand the problem, both magnetic fields B₁ & B₂ need to change direction, due to the change in current (I) by replacing the positive with a negative ion.

 

Your thoughts,

 

My apologies, but I can't appear to upload the attached file. I'll try again later!!

Please find attached!

You are correct that reversing B will give the same force on the opposite charge.

 

What about E in the region between the plates? You are supposed to getting no deflection there.

Thank-you swansont for you post.

 

so using Lorentz force, if a negative ion is introduced the electric field also must be changed? Please find attached.

Thank-you swansont for you post.

 

so using Lorentz force, if a negative ion is introduced the electric field also must be changed? Please find attached.

With the attachment, I meant to say E and B₂ need to be reversed, if I assume B₁ doesn't.

hwork-phys(rev).pdf

Yes, the E and B in the deflection-free region have to be reversed, and you previously concluded the B in the deflection region had to be reversed.

Thanks swansont, solved it.