Why does an aluminum ring fly off a current-carrying coil?

[skyliner34]

Can anyone explain how flying ring works?
like the demostration whith a magnetic coil connected to AC poer and an aluminum ring. the ring was placed on the top of the coil and althought aluminum is a non magnetic, the ring was thrown to the ceiling.
can anyone tell me why there was force on the ring
and
why the ring went up?
juz like this

WWW.physics.montana.edu/demonstrati...tyandmagnetism/demos/thompsonsflyingring.html

 

[pam]

The oscillating magnetic field induces an emf and thus a current in the ring.
The magnetic field exerts an upward force on the currentin the ring.

 

[skyliner34]

The oscillating magnetic field induces an emf and thus a current in the ring.
The magnetic field exerts an upward force on the currentin the ring.

can u show me by darwing th diagram?
cuz i m not quiet get how it works
thanks for helping

 

[pam]

I'll try to describe it in words. The magnetic field is mostly upward but it weakens as it gets higher, which leads a slight horizontal component to the field lines.
The oscillating B field induces current in the horizontal plane of the ring.
The horizontal component of B exerts an upward force on the current in the ring.

 

[skyliner34]

one more question
why a smaller aluminum ring will fly higher, and a copper will lower ?

 

[pam]

Aluminum is lighter.