4.2. The Black Emitter

A hollow space which should be heated up to 1000°C must be made out of fire-proof material, as for example: iron!

 

Have a look at the cross section of this iron stick!

 

 

As you see from the figure it is easy to reconstruct: You need two short iron sticks with diameters of 6 and 12 mm. Into the thicker one you drill a hollow space to fix the thinner one in. At the end you drill into the front surface an aperture with 2 mm diameter.

 

During the whole arragemant is heated up you look at the aperture of the front surface.

At low temperature the aperture of the hollow-space looks black.

 


At a certain temperature the aperture is glowing just with the same intensity as the surrounding surface of the stick, so that the opening is almost no longer to be seen.

 

We continue heating the stick and at this temperature you see the aperture emitting red light with even more intensity as the rest of the stick!

This is what we call a "black emitter".

 

Und der brave Bauersmann

denkt, nu wat geit mich dat an.

Wilhelm Busch

(Look it up in a professional translation of the work of W.B.. May be yahoo will be your pathfinder.)

 

How we are concerned by the phenomena of a black emitter you can find out if you have a look at the "curtainless" window.