(a) Why are infra-red waves often called heat waves? Explain.
(b) What do you understand by the statement, "Electromagnetic waves transport momentum"?
(a) Infrared waves whenever encounter any object, they cause entire atoms and molecules to vibrate.
And due to these vibrations, the internal energy and temperature of the object increases.
Due to this infra red waves are often called as heat waves.
(b) Electromagnetic waves carry energy. It means that they also carry momentum and exerts radiation pressure.
The energy and momentum transported are not continuously distributed over the wave front. Energy and momentum are transported by photons in discrete packages.