Lab: Law of Reflection
The Law of Reflection states that the angle of incidence equals the angle of reflection. This is
true for all reflections. In this experiment, students practice using plane mirrors and measuring
angles to comfirm the law.
Objective:
1. To measure various angles of incidence on a plane mirror and verify that the angle of reflection in each case is
always equal to it.
2. To use the Law of Reflection to locate a virtual image behind a plane mirror.
Equipment: Plane mirror, paper, protractor, ruler, paper and board.
Procedure: 1. Position a plane mirror vertically on a piece of paper. Place an object somewhere in front of the
mirror. Look at the reflection of the object in the mirror, and mark these three things: the position of the object,
the point at the base of the mirror where the light from the object reflects. The line of sight of the observer.
2. Remove the object and mirror. Draw the normal to the mirror at the point where the reflection occurred.
measure the angles of incidence and the angle of reflection. Are they the same?
3. Extend the line of sight from the eye behind the mirror. Draw a line perpendicular to the mirror and which
touches the object. Extend this line on the far side of the mirror. Where these two lines intersect is where the real
image of the object is formed. Draw in the real image.
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4. Measure the distance from the mirror to the real image, and the distance from the mirror to the object. What
do you observe?
5. Repeat the experiment at least 3 times, using diferent distances and angles.
Results: Make a table of your results.
Trial #
1
2
3
4
i
r
d1
Conclusions: What can you say about:
The angle of incidence and the angle of reflection?
The distance from the mirror to the image and the distance from the mirror to the object?
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