By comparing a spectrum from the moving object with a spectrum from the same elements at rest, you can calculate the velocity of the object using the Doppler shift formula. Chapter 3 Review Questions 1. Refraction is the bending of light rays upon passing from one transparent medium to another. For example, light that passes from air through a glass lense and then back to air will be bent from its original direction in a very predictable way. Reflection is the bouncing of light off of a reflective surface, such as a mirror.
Reflection simply changes the direction of the light.
The direction change can be controlled in a very accurate way if the shape of the mirror is precisely known. Refractive telescopes gather light from a large area, direct that light through a precisely shaped lense, which focuses the light onto a smaller area which can be viewed by a person or detector. Reflective telescopes use spherical, elliptical, parabolic, or hyperbolic shaped mirrors to focus light from a large area onto a smaller area. By using several mirrors, the light path can be contained into a smaller area. This means that different color light will be focused differently when passed through the lense, resulting in a blurred image.