Chapter 3  (Refraction ) 1. With regard to refraction: a. it is a change in direction of light when it passes from one transparent      medium into another of different optical density b. light is deviated away from the normal when it enters an optically      dense medium from a less dense medium. c. the velocity of light is changed during refraction d. the wavelength of the light is changed during refraction e. the angle of refraction is different for light of different wavelength   Answera.T   b.F   c.T    d.T   e.T Refraction is defined as a change in direction of light when it passes  from one transparent medium into another of different optical density.  Light is deviated towards the normal when it enters an optically dense medium form a less dense medium. The reverse applies. The velocity of light is changed during refraction but not its frequency or wavelength. The angle of refraction is different for light of different wavelengths.  Light of shorter wavelength is deviated more than one with longer wavelength. .      2. The following are true about the refractive index of a material: a. the absolutie refractive index of a material is always greater than its      refractive index b. the refractive index of a material is usually measured with ultraviolet light c. the refractive index of a medium differs for light of different wavelengths d. the deviation of light increases with the increase in refractive index of the      material that it enters e. a material with high refractive index will reduce the speed of light more      than one with lower refractive index   Answera.T  b.F  c.T  d.T  e.T The absolute refractive index of a material is the velocity of light in  vacuum divided by velocity of light in that medium. The refractive index of a material is the velocity of light in air divided by velocity  of light in that medium. As ligth travels faster in vacuum than air, the absolute refractive index of a material is always greater than its refractive index. The refractive index of a material is different for different wavelength and in general it is usually measured with yellow sodium flame. The refractive index of a medium differs for light of different wavelengths, however, the difference is usuallly slight.  A material with a higher refractive index will deviate the light more  and reduce the speed of light more than one with lower refractive index. The frequency and wavelength of a light is not change as it travels from one medium into another.