Light Bounces at a Matching Angle

You'll learnwhich line every angle of reflection is measured from, why rough paper still obeys the law, and why covering half a mirror only dims the image.

A ray bounces off a mirror as steeply as it arrived - once you measure from the right line. The same law runs a sheet of rough paper, facet by facet, and a covered mirror keeps its whole image. Eleven short steps; press Next for each one.

11 STEPS · 6 QUICK CHECKS · FROM THE NORMAL · ROUGH STILL OBEYS IT · v2

angle in equals angle out, from the normal · rough paper obeys it too

Before you start

What you're looking at

A ray of light meeting a flat mirror. The dashed line is the normal, the reference line at right angles to the surface.

The question

Which line are the angles measured from, and what does rough paper do to the law?

Step 1 / 11