What physical property of visible light was Herschel observing when he discovered infrared waves?

Responses

density
density

wavelength
wavelength

amplitude
amplitude

temperature

1 answer

When Herschel discovered infrared waves, he was observing the temperature of the light, specifically how much heat different regions of the spectrum produced. He used a thermometer to measure the temperature of the light beyond the visible spectrum and found that there was a region beyond red light that produced higher temperatures, leading to the discovery of infrared radiation.