Visible light in Electromagnetic spectrum has wavelength of about 400 nm to 750 nm. The speed of light in vacuum is the highest speed attainable in nature and is equal to c = 3 x 108 m/s. The path of light is called a ray of light, and a bundle of such rays constitutes a beam of light.
The phenomenon of change in direction of propagation of an obliquely incident ray of light that enters from one medium to the other medium, at the interface of the two media is called refraction of light.
