Where does the force come from?

[ashishsinghal]

We have a circular non conducting ring placed in a uniform magnetic field with its direction perpendicular to the plane of the ring. There is a charge present on the ring. The field changes with a rate dB/dt. By lenz law we know that the ring will start rotating to form a current that will oppose change in B.

But if we apply basic rules of physics - Where does this force required to move the ring come from? there is only magnetic field which cannot affect a rest charge.

 

[Dale]

The field changes with a rate dB/dt. ... there is only magnetic field which cannot affect a rest charge.

By Faradays law, if you have a changing B field this will induce an E field. So it is not correct that there is only a B field, there is both E and B.