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Experiment: two spherical mirrors, where the thermocouple is in the focus of one of them. The temperature of this thermocouple can be seen by the offset of the indicator on the galvanometer.
- place the flame in the focus of the second mirror - the indicator shifts significantly.
- massive body cooled in liquid nitrogen is placed in the focus of the mirror. The indicator is shifted to the other side.
- Install a piece of ordinary glass between the body and the mirror. The offset of the indicator has decreased significantly.
Explain the nature of the observed effects :-) Cold rays?
In russian: