What did Sir William Herschel measure just beyond the visible red band in 1800?
Answer
Invisible rays that carried heat, which he termed calorific rays.
Sir William Herschel, while investigating the heating effects of sunlight split by a prism, observed that a thermometer placed just outside the visible red portion of the spectrum registered an increasing temperature, even though no visible light was present there. This led him to the revolutionary conclusion that invisible rays carrying heat existed. He logically named these newly detected, invisible rays 'calorific rays,' thereby pinpointing the electromagnetic region that would later be called infrared radiation.
Related Questions
What did Sir William Herschel measure just beyond the visible red band in 1800?How does a thermopile convert infrared radiation into a signal?What physical change does Samuel Langley's bolometer measure upon absorbing thermal radiation?How is the infrared (IR) region of the electromagnetic spectrum defined by wavelength?What is the fundamental operational difference between thermal detectors and quantum detectors?What mechanism describes the operation of Photovoltaic Detectors?What do Passive Infrared (PIR) sensors, often pyroelectric, primarily look for in a moving target?Which existing technology did Sir William Herschel use as his primary detector for measuring radiation effects?In quantum detectors, what specific energy transition occurs when an incoming infrared photon interacts with the material?What specific contribution did Sir William Herschel make regarding the infrared sensor lineage?