Why does light bend towards the normal

Similarly,when a ray of light passes from denser to rarer medium,it bends away from Normal. When a ray of light passes from rarer medium to denser medium ,it bends towards the normal. A transparent substance medium in which the speed of light is less is known as optically denser medium.

Glass is an optically denser medium than air and water. Case 1: When light rays travel from optically rarer medium to denser medium then they bend towards normal.

As the light goes from an optically denser to an optically rarer medium, it bends away from the normal. Hence, the angle of refraction is greater than the angle of incidence. Air is an optically rarer medium as compared to glass and water. Optically Denser Medium: A medium in which the speed of light is less, is known as optically denser medium. There are two points that is to be kept in mind: 1. A medium in which the speed of light is more is known as Optically Rarer medium. Air is optically rarer medium as compared to glass and water.

A medium in which speed of light is less is known as optically denser medium. If Refractive index is more bending of light is more and speed of light will be less.

Complete answer: When the light travels from one medium to another, the velocity of light changes. To compensate this change, wavelength changes too or vice versa.

Due to these compensatory changes, frequency remains constant. The property of light that does not change when it travels from one medium to another is frequency. Learn more. Why does light bend towards the normal when passing from a rarer to a denser medium?

Ask Question. Asked 6 years, 8 months ago. Active 5 years, 2 months ago. Viewed 20k times. Improve this question. Add a comment. Active Oldest Votes. Improve this answer. Community Bot 1. A rainbow is caused because each colour refracts at slightly different angles as it enters, reflects off the inside and then leaves each tiny drop of rain.

A rainbow is easy to create using a spray bottle and the sunshine. The centre of the circle of the rainbow will always be the shadow of your head on the ground.

The secondary rainbow that can sometimes be seen is caused by each ray of light reflecting twice on the inside of each droplet before it leaves. This second reflection causes the colours on the secondary rainbow to be reversed. Red is at the top for the primary rainbow, but in the secondary rainbow, red is at the bottom. Learn more about the many different kinds of rainbows and how they are formed from the Atoptics website — Rainbows reflect and Rainbow orders.

Learn more about human lenses, optics, photoreceptors and neural pathways that enable vision through this tutorial from Biology Online. Add to collection. Activity ideas Use these activities with your students to explore refration further: Investigating refraction and spearfishing — students aim spears at a model of a fish in a container of water.

When they move their spears towards the fish, they miss! Angle of refraction calculator challenge — students choose two types of transparent substance. They then enter the angle of the incident ray in the spreadsheet calculator, and the angle of the refracted ray is calculated for them.

There is no ultimate change in the direction that the light is traveling. This small detail will only be the case under two conditions:. The diagrams below provide a contrast to the rectangular plot of grass and the rectangular block of glass.

Both diagrams involve the refraction of a tractor or a light wave as it passes into and out of a triangular plot of grass and a triangular block of glass. Copy this diagram onto a sheet of paper and apply your understanding of refraction principles to predict the path of the tractor and the light wave as it travels through the triangle-shaped obstacle. Draw the path on your separate sheet of paper and then click on the button below to check your answer.

See Answer. Another means of approaching the subject of the direction that light bends when crossing a boundary between two media is through the Least Time Principle. This Least Time Principle is sometimes stated as follows:. A useful analogy to understanding the principle involves a lifeguard who has become aware of a drowning swimmer in the water. In order to save the drowning swimmer, the lifeguard must run through the sand, cross the boundary between the sand and the water, and then swim through the water to the drowning swimmer.

Of course, the guard must reach the swimmer in as little time as possible. Since the guard can run faster on sand than she can swim in water, it would make sense that the guard covers more distance in the sand than she does in the water. In other words, she will not run directly at the drowning swimmer. The optimal entry point into the water is the point that would allow the lifeguard to reach the drowning swimmer in the least amount of time.

Obviously, this point would be at a location closer to the swimmer than to the guard. The diagram below depicts such an entry point. Observe in the diagram, that minimizing the time to reach the swimmer means that the lifeguard will approach the boundary at a steep angle to the normal and then will bend towards the normal upon crossing the boundary. This analogy demonstrates that the Least Time Principle would predict the following direction of bending:.

This is the very generalization that was made earlier on this page. Using the above principles and logic to explain and predict the direction that light refracts when crossing a boundary will be a major objective of this unit. Rather than merely restating the principle, you will be asked to apply it to a variety of situations such as those in the Check Your Understanding section below.

Part of accomplishing this task will involve remembering the principles. For this reason, the following useful mnemonics are offered. A mnemonic is a tool used to help one remember and difficult-to-remember idea. Of course, there is always the risk that the mnemonic will be forgotten. You can remember FST fast to slow; towards by simply thinking about those Freaky Science Teachers that you have had through the years.