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Reflection And Refraction

Experiment 11 ~ Reflection and Refraction

Purpose:

The purpose of this experiment is to investigate two of the basic laws of optics, namely the law

of reflection and Snell’s law.

Theory:

Reflection and refraction are two commonly observed optical properties of light. Whenever a

light strikes the surface of some material at an angle, part of the wave is reflected and part is

transmitted (or absorbed). Due to refraction, the velocity of transmitted light is less than the

velocity before it entered the medium. The denser the medium, the more the light is slowed

down. This is due to interaction between the light and the orbiting electrons in the atoms

comprising the material.

The law of reflection is stated in your text. It says that the angle of incidence equals the angle of

reflection, as shown in Figure 1.

Figure 1

= α

Figure 2

When light travels from one material into another, it not only may change velocity, but it may be

bent at a different angle in the new medium than the angle at which it entered (Figure 2). Snell’s

law states the relationship between the indices of refraction of the two materials, and the light’s

angle of incidence and angle of refraction:

sin α = n

sin β

Equipment:

• ray box

• semicircular solid block

• semicircular hollow plastic block

• polar graph paper

• tape

Reflection And Refraction