Which of the following statement is not true ?

Options

A. the wavelength changes when it travels from one medium to another.
B. The frequency changes when it travels from one medium to another.
C. The speed changes when it travels from one medium to another.
D. They travel is straight line in a given medium.

Answer

B

Explanation

Thermal radiation travels in straight lines, like light.
Thermal radiation obeys the law of refraction.
Hence, when it travels from one medium to another, its wavelength and speed changes whereas frequency remains unchanged as frequency is the characteristics of source of thermal radiation.