Awesome short video a great display of the power of moving electrons

[Moontanman]

This demonstration of inductive heating is awesome...

 

 

Kinda makes you want to run out and buy some copper pipe right now...

 

 

Seriously, is this real or some sort of trick?

Edited April 6, 2014 by Moontanman

[John Cuthber]

It's real.

There are a fair few sites which deal with the subject.

Here's another

http://www.mindchallenger.com/inductionheater/

[swansont]

Very real. The system acts as a step-down transformer, so the eddy currents in the cube are much higher than in the coil, which is water-cooled (telling you there's probably a decent amount of resistive heating going on, despite the relatively low resistance)

[Moontanman]

Very real. The system acts as a step-down transformer, so the eddy currents in the cube are much higher than in the coil, which is water-cooled (telling you there's probably a decent amount of resistive heating going on, despite the relatively low resistance)

 

 

so that's why they used a copper pipe!

[Enthalpy]

Keeping the inducing coil cold is difficult.

 

The number of turns doesn't help, at least at low frequencies. In the same shape, if you put N times more turns, having each N times less cross-section, and total length N times bigger, then the (low frequency) resistance is N² times bigger. The current is N time smaller, so the resistive losses stay the same. (Eddy currents and skin effect don't scale like this, hence I insist on low frequency)

 

What helps is:

- Copper versus more resistive material

- Resistivity increasing at heat

- If the heated material is ferromagnetic (...not too hot hence), then current flows only in a much thinner skin at its surface, and the resistance is much bigger. This is the case when the surface of a steel part is heated by induction, then this surface is cooled quickly by the deeper matter of the part, and this hardens the steel at the surface only.