Question

why uv rays does not require any material medium to travel

Answer 1

UV rays are light rays and light does not need medium to travel.Its an electromagnetic(EM) wave.All EM waves travel independent of medium.

Answer 2

Light doesn't need a material medium to travel because speed of light is constant . It is independent of any medium it travels through. And the ultraviolet rays are also light rays ( from the sun) . And light travels through vacuum.