Question

What do you mean by the invisible spectrum? How will you investigate the existence of radiation beyond the red and violet ends of the spectrum?

Answer 1

Hint: A spectrum which is a condition that is not limited to a specific set of values. In the electromagnetic spectrum the electromagnetic waves are arranged according to their frequencies and also with respect to their wavelength. The frequency ranges in the electromagnetic spectrum are divided into different bands and these bands are called by different names.


Complete step-by-step solution: -
Invisible spectrums are the part of the spectrum beyond the red and violet end. Invisible our eyes do not respond to the invisible spectrum and if different radiations from the red part of the spectrum to the violet end and beyond it are made to strike on the silver-chloride solution. From this it is observed that from the red to the violet end the solution remains unaffected and beyond the violet end the solution turns violet and at the final the solution turns dark brown.
The radiations which exist beyond violet end of the spectrum are chemically more active than the visible light
 A thermometer with a blackened bulb is moved from the violet end towards the red end from this it observed there is a slow rise in temperature but when it is moved beyond the red region temperature is suddenly increased these observe showed that portion of spectrum beyond the red end as certain radiations due to which a heating effect is produced but they are not visible.

Note: Students Infrared have energy ranging from $1.7eV-1.24meV$ and visible rays have energy ranging from $3.3eV-1.7eV$ . Gamma rays which are formed in the radioactive decay will have energy ranging from kiloelectron volts to 8 megaelectronvolts. Gamma rays are produced by four different nuclear reactions and the four nuclear reactions are nuclear fission, nuclear fusion, gamma decay and alpha decay.