Question

Infrared radiation was discovered in 1860 by

• A. William Wallaston
• B. William Herschel
• C. William Roentgen
• D. Thomas Young

Answer 1

Answer: (B)

William Herschel

Herschel was testing filters for the sun so he could observe sun spots. When using a red filter he found there was a lot of heat produced. Herschel discovered infrared radiation in sunlight by passing it through a prism and holding a thermometer just beyond the red end of the visible spectrum.This thermometer was meant to be a control to measure the ambient air temperature in the room. He was shocked when it showed a higher temperature than the visible spectrum. Further experimentation led to Herschel's conclusion that there must be an invisible form of light beyond the visible spectrum.