Eddy currents

[Pranav Jha]

i know i haven't understood the concept of eddy current and that is why i am posting this question:
why are EDDY CURRENTS circular?

 

[Pranav Jha]

please also explain this answer that statement that i found on : http://wiki.answers.com/Q/What_is_an_eddy_current
"When time-varying magnetic field is applied to electrical machines like transformers, a time-varying emf is induced in the transformer cores(i get this). A SHORT CIRCUIT OCCURS AT THE MOLECULAR LEVEL IN THE CORE(this, i don't quiet understand)"