Measure Reflection Angles from the Normal - Practice 1

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The normal is a line perpendicular to the surface at the point where a ray meets it. For a flat ideal mirror, the reflection angle equals the incidence angle when both are measured from that normal, not the mirror surface.

Worked example

A ray arriving 35 degrees from the normal reflects 35 degrees from the normal, which is 55 degrees from the surface.

A flat mirror has a normal perpendicular to its surface. An incoming ray and an outgoing ray each make 35 degrees with the normal on opposite sides. Arrow directions show arrival and reflection.

Question 1 An ideal mirror ray arrives at 10 degrees from the normal. What is its reflection angle from the normal, in degrees? Answer

Question 2 An ideal mirror ray arrives at 15 degrees from the normal. What is its reflection angle from the normal, in degrees? Answer

Question 3 An ideal mirror ray arrives at 20 degrees from the normal. What is its reflection angle from the normal, in degrees? Answer

Question 4 An ideal mirror ray arrives at 25 degrees from the normal. What is its reflection angle from the normal, in degrees? Answer

Question 5 An ideal mirror ray arrives at 30 degrees from the normal. What is its reflection angle from the normal, in degrees? Answer