# Refraction Definition and Background

Refraction is another behavior that light exhibits as it interacts with different media. It is simply defined as the bending of light due to its change in speed as it strikes on different materials with various densities. The extent of refraction of light is dependent on the medium’s refractive index.

Every material has a refractive index, a dimensionless number that describes how fast light travels through it. The higher the refractive index of a material, the more that light will bend as it passes through it. This number can be obtained using the Snell’s law or the law of refraction .

Similar to reflection, refraction also involves the angles that the incident ray and the refracted ray make with the normal to the surface at the point of refraction. But unlike reflection, refraction depends on the media through which light rays are traveling. This dependence is explicitly made known in material’s refractive index. In this laboratory activity, you will compute the refractive index of various media using the Snell’s law.

In the law of refraction, n1 sin I = n2 sin r.

## Refractive Index of Various Lenses Learning Objectives:

By the end of this lab activity, you will be able to:

• Explain how light is refracted in various media.
• Describe the refractive index of various lenses.

## Refraction Lab Materials:

• eyeglasses lens
• magnifying lens
• camera lens
• laser pointer
• protractor
• calculator

## Refractive Index of Various Lenses Lab Procedure:

1. Position the laser at an angle of 300 with the normal line of the lens. This will be the angle of incidence for all set-up.
2. Label the lens according to their use or type.
3. Shine the laser pointer on each lens and observe how the light bends. For each lens, measure the angle of refraction of a laser using a protractor.

Safety Alert! Be sure not to point the laser pointer to your eyes or classmates’ eyes. This may cause damage to the eyes if not used properly.

1. Do three trials for each lens.
2. Record your measurements in the given table and describe the refraction index of various lenses based on how light is refracted in it.

## Refractive Index Post-lab Questions:

1. Is refraction evident in the three lenses? What made you say so?
2. In which lens is light most bent? Least bent?
3. Which lens has the greatest refractive index? Least refractive index?
4. Is there any relationship that you can infer from the activity?
5. What is the relationship between the bending of light and the refractive index of the material?

## Refraction Worksheets - Word Docs & PowerPoints

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