When switch is closed the ring will jump upward, but why?
I know that when the switch is closed a current is established in the solenoid. The current flow is from + to - so that the direction of the magnetic field in the solenoid is downward (according to right hand rule). The magnetic flux increases according to Lenz's law. So, the ring should produce a magnetic field in the opposite direction. In my book it is stated that the ring will feel a force upward. I know that the induced current which is in a magnetic field will experience a force but I don't know how to identify the direction of this force. How can I know that it's upward; which rule should I use?