Magnetic interaction between moving and stationary charge

[whatisreality]

Homework Statement

A metal sphere, with charge q₁=-2.80μC is held still and off the ground on an insulating rod. Another smaller metal sphere with charge q₂=-7.80μC is projected towards q₁. When the two spheres are 0.80m apart, q₂ moves at 22ms^-1.
Assume the spheres are point charges, neglect gravity. What is the magnitude of the magnetic force of q₂ on q₁ when the spheres are 0.5m apart?

Homework Equations

F=qvB, I think...

The Attempt at a Solution

I'm a bit confused about why the magnetic force on the stationary sphere isn't zero. It isn't moving. There may be current in it as electrons are repelled by the approaching sphere, but if we're treating both as point charges this becomes irrelevant, doesn't it? So there's no reason it would feel magnetic force.

Even assuming it does feel a magnetic force, I have no idea which equation to use to find its magnitude. I don't know v or B at 0.5m apart!

 

[mfb]

So there's no reason it would feel magnetic force.

In other words, the force is zero.

Weird sort of problem. You can still calculate the total force, which includes the electric component.

(I deleted your other thread as it is fully redundant to this one)