A prism is a block of glass with three rectangular and two triangular surfaces
In this lesson, you'll learn about the prism and what prisms do to white light. You'll explore the properties of light waves, as well as the concept of refraction, which causes white light to bend in a prism and spread out into the different spectrum of colors.
What is a Prism?
Have you ever wondered why there are rainbows? Did you ever see a prism work and wonder why a prism seems to create rainbows? Well, in this lesson you'll learn about prisms, how they work, why they work, and what applications they may have to everyday phenomena.
A prism is an object made up of a transparent material, like glass or plastic, that has at least two flat surfaces that form an acute angle (less than 90 degrees). White light is comprised of all the colors of the rainbow. When white light is passed through a prism, the colors of the rainbow emerge from the prism much like in the figure here. We'll learn more about why a prism spreads white light out into the colors of the rainbow.
A prism
Definition of Refraction
Have you ever noticed that people standing in a pool always look shorter than they really are or that a spoon in a glass of water seems to be bent? The reason why these phenomena occur is because of the concept of refraction, which is simply the bending of a light wave. In order to further understand what refraction is and why it occurs, we need to look at what happens to light when it goes from one medium to another (like from air to water or a vacuum to air).
Index of Refraction
The speed of light in a vacuum is denoted by the letter c and has a value of 300,000,000 meters per second (m/s). When light goes from a vacuum to another medium, light slows down. How much it slows down is dependent on something called the index of refraction, which is denoted by the letter n. The index of refraction is a property of a material (or medium). When light goes into a denser medium, it slows down more. The denser the material, the slower light will travel through that medium. The speed of light in a material, denoted by v, changes according to the following formula: