What is IH?
When the magnetic flux created at the coil passes through the bottom of the pot placed on the top plate, eddy current is generated around the flux.

This eddy current then is transformed into heat by the resistant element of the pan and heats up the pan for cooking.

But the top plate will remain cooler to the touch than other cooking surfaces (Say, a regular electric or gas ranges) as it in only warmed from direct contact with the hot pan, not actively heated itself.