Spectrum — Question 12

Two properties of infrared radiations which are similar to the visible light are as follows:

1. Infrared radiations travel in a straight line like visible light, with a speed of 3 x 10⁸ m s^-1 in air or vacuum.
2. They obey the laws of reflection and refraction like visible light.

Two properties of infrared radiations which differ from the visible light are as follows:

1. Infrared radiations have wavelength in the range of 8000 Å to 10⁷ Å whereas wavelength of visible light is the range of 4000 Å to 8000 Å.
2. Infrared radiations do not affect ordinary photographic plate whereas visible light affects photographic plate.