One major principle discussed in both Unit 13 and Unit 14 of The Physics Classroom Tutorial is the line of sight principle: In order to view an object, you must sight along a line at that object; and when you do light will come from that object to your eye along the line of sight. This…
We have already learned that a lens is a carefully ground or molded piece of transparent material that refracts light rays in such a way as to form an image. Lenses serve to refract light at each boundary. As a ray of light enters a lens, it is refracted; and as the same ray of light exits the lens,…
The Anatomy of a Lens If a piece of glass or other transparent material takes on the appropriate shape, it is possible that parallel incident rays would either converge to a point or appear to be diverging from a point. A piece of glass that has such a shape is referred to as a lens….
Most of our discussion of refraction in this unit has pertained to the refraction of light at a distinct boundary. As light is transmitted across the boundary from one material to another, there is a change in speed, which causes a change in direction of the light wave. The boundaries that we have been focusing on have been…
One of nature’s most splendid masterpieces is the rainbow. A rainbow is an excellent demonstration of the dispersion of light and one more piece of evidence that visible light is composed of a spectrum of wavelengths, each associated with a distinct color. To view a rainbow, your back must be to the sun as you look at an approximately…
Dispersion of Light by Prisms In the Light and Color unit of The Physics Classroom Tutorial, the visible light spectrum was introduced and discussed. Visible light, also known as white light, consists of a collection of component colors. These colors are often observed as light passes through a triangular prism. Upon passage through the prism, the white light is separated into its…
In the previous part of Lesson 3, the phenomenon of total internal reflection was introduced. Total internal reflection (TIR) is the phenomenon that involves the reflection of all the incident light off the boundary. TIR only takes place when both of the following two conditions are met: · a light ray is in the more dense medium and…
A common Physics lab is to sight through the long side of an isosceles triangle at a pin or other object held behind the opposite face. When done so, an unusual observation – a discrepant event – is observed. The diagram on the left below depicts the physical situation. A ray of light entered the…
In a previous part of Lesson 2, we learned about a mathematical equation relating the two angles (angles of incidence and refraction) and the indices of refraction of the two materials on each side of the boundary. The equation is known as the Snell’s Law equation and is expressed as follows. ni • sine (Θi) = nr * sine…
Refraction is the bending of the path of a light wave as it passes across the boundary separating two media. Refraction is caused by the change in speed experienced by a wave when it changes medium. Lesson 1, focused on the topics of “What causes refraction?” and “Which direction does light refract?” In that lesson, we learned that light…