Chapter 28: Reflection and Refraction Flashcards
Describe the difference between reflection and refraction.
Reflection: When light is returned into the medium in which it came from.
Refraction: When light crosses from one transparent material into another.
Describe Fermat’s principle of least time.
Light travels the path that takes the shortest time (i.e. a straight line), even if it is deflected by a mirror, it still travels in a straight line.
Describe the Law of Reflection.
The law of reflection states that when a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection.
Describe the two types of mirrors.
Plane mirror: the image is just as far behind the mirror as the object is in front of the mirror. This is a virtual image since the light rays do not actually come from this point. The light enters the eye exactly how it would have physically if the object really were at the image location.
Diffuse reflection: When light is incident on a rough surface, it is reflected in many directions.
Describe the Law of Refraction.
When light travels from one medium to another, it generally bends, or refracts. (Snell’s Law)
When light ray is incident normally, only speed changes and direction of light remains the same.
When light ray passes from rarer medium to denser medium, it bends towards the normal.
When light ray passes from denser medium to rarer medium, it bends away from the normal.
What is the critical angle?
The minimum angle of incidence inside a medium at which a light ray is totally reflected.
What is total internal reflection?
A complete reflection of a ray of light within a medium such as water or glass from the surrounding surfaces back into the medium. The phenomenon occurs if the angle of incidence is greater than a certain limiting angle, called the critical angle.
