Refraction why light bends

This slight difference is enough for the shorter wavelengths of light to be refracted more. 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. Light and sight: true or false? This activity can be done individually, in pairs or as a whole class. Useful links Learn more about the many different kinds of rainbows and how they are formed from the Atoptics website — Rainbows reflect and Rainbow orders.

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. Traveling from a more dense medium to a less dense medium is like traveling from a slow medium to a fast medium; such a light ray will bend away from the normal. Traveling from a less dense medium to a more dense medium is like traveling from a fast medium to a slow medium; such a light ray will bend towards the normal.

Traveling from a medium with a high n value to a medium with a low n value is like traveling from a slow medium to a fast medium; such a light ray will bend away from the normal.

Traveling from a medium with a low n value to a medium with a high n value is like traveling from a fast medium to a slow medium; such a light ray will bend towards the normal. In each diagram, draw the "missing" ray either incident or refracted in order to appropriately show that the direction of bending is towards or away from the normal.

Arthur Podd's method of fishing involves spearing the fish while standing on the shore. The actual location of a fish is shown in the diagram below. Because of the refraction of light, the observed location of the fish is different than its actual location.

Indicate on the diagram the approximate location where Arthur observes the fish to be. Must Arthur aim above or below where the fish appears to be in order to strike the fish? See Answer Arthur must aim at a position on the water below where the fish appears to be. Since light refracts away from the normal water to air as Arthur sights at the fish, the refracted ray when extended backwards passes over the head of where the fish actually is.

For the following two cases, state whether the ray of light will bend towards or away from the normal upon crossing the boundary. See Answer Case A: This ray is traveling from slow high n value to fast low n value ; it will bend away from the normal. Case B: This ray is traveling from fast low n value to slow high n value ; it will bend towards the normal. Physics Tutorial. My Cart Subscription Selection. Student Extras. Flickr Physics Photo. We Would Like to Suggest Sound travels faster in warm air, so the speed of sound near the ground increases.

Sound waves bend toward a region in which their speed will be slower, so therefore they tend to bend away from the ground, resulting in sound that does not seem to transmit well Figure 2. Light travels a bit faster in less-dense air than in denser air. Under this condition, seeing a mirage is a common experience. The road ahead may appear to be wet, yet when you get there, the road is dry.

The explanation for this is similar to the bending of sound waves. Rather than light reaching us in straight lines as it would in constant-density air, when traveling through the hotter region near the road, the wavefronts of light speed up and curve upward before reaching our eyes Figure 3.

We are not seeing a mirror image of the sky, as an actual wet patch would show, but light refracted by the warmed air near the ground. As its wavefronts graze the upper atmosphere, light bends downward Figure 4. This means we see the Sun higher in the sky than it actually is. Atmospheric refraction explains why we see longer daylight time than we would without refraction. When we see the Sun touching the horizon at sundown, it has already dropped below it or, strictly speaking, Earth has already turned away from the Sun.

Atmospheric refraction often deceives our senses. The familiar oranges and reds of the sky occurring at sunrise or sunset are due to the absence of higher-frequency blues and violets.

Hence the reddish-orange colors of sunrises and sunsets. At any given time, half of planet Earth is in sunshine.