Why tesla coil is air-cored to operate efficiently at high freq?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: d a <btoc3000@xxxxxxxxxxxx>


Hi all,



I have three theoretical questions here:


I read this from a website: "A normal transformer users an iron core 
in order to operate at low frequencies, whereas the Tesla Coil is 
air-cored to operate efficiently at much higher frequencies".



I understand that a normal transformer relies on turn ratios and the 
air core is there to reinforce the magnetic flux.



May I then ask, why is an iron core only required in low frequency 
operation and why do we use an air-core for high frequency operation?


Lastly, I read this from another website: " In the Tesla "swing", the 
kick is supplied by the AC electrical current moving back and forth". 
Can someone elaborate on this please? Is it actually referring to the 
LC circuit - both the secondary and primary operating at the same 
frequency that reinforce each other?



Thank you very much for your kind attention.


Regards
Sam