Question

fill in the blank question
traditional thermometers are based upon the idea that substances expand or contract at set rates due to changes in temperature, whereas modern thermometers measure the intensity of the
radiation emitted from objects such as the human body.

Explanation:

Traditional thermometers rely on thermal expansion/contraction. Modern ones, like infrared thermometers, measure infrared radiation. Infrared is a type of electromagnetic radiation related to temperature (Stefan - Boltzmann law: \(P=\sigma AT^{4}\), where \(P\) is power radiated, \(\sigma\) is Stefan - Boltzmann constant, \(A\) is surface area, \(T\) is temperature). Human body emits infrared which intensity depends on its temperature.

Answer:

infrared