Mirrors: Reflection and Refraction at a Medium

(A Scratch program for simulating optics)

In this example, the blue block is representing a transparent medium (like glass or water). The darkest red arrow is the light going in, and the 2 orange arrows are the reflected and refracted light. The reflected light ray (the one pointing away from the medium) is being reflected at the same angle as the one going in. The angle (alpha) of the input arrow is controlled by the alpha slider. The program automatically calculates the changes to the reflected and refracted arrows.

The orange arrow in the medium is being refracted (the light bends into the medium) as it leaves the air and enteres the medium. This bending occurs because the medium is optically thicker (more dense) than the air. The slider n2 changes the optical thickness (called `index of refraction') of the medium between 1.0 and 5.0, which then changes the angle of the refracted arrow.

• The thicker the medium (higher index of refraction), the more the arrow is refracted.
• The less dense the medium, the less the arrow is refracted.
• If n2=1.0, the medium is like the air (n1=1.0) on the left, and thus the arrow is not affected.