Reflection From a Plane Mirror

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To measure the angles of incidence and reflection from a plane mirror, and the image distance, d_i, and the object distance, d_o.

Put a sheet of notebook paper on the piece of cardboard.
Place the mirror upright and with edge parallel to the notebook paper line.
Place a pin approximately 5 cm in front of the left side of the mirror.
Place a second pin up against the mirror about halfway along the length.
Using a third pin, line up pin 2, pin 3 and the image of pin 1 in the mirror.
Draw a line segment connecting pin 1 and pin 2. Draw another segment connecting pin 2 and pin 3.
Move pin 2 about 3 cm to the right and repeat step 4.
Extend the line segments connecting pin 2 and pin 3 behind the mirror line. Where these two lines meet is the virtual location of the image pin. Call it 1'.
Draw a perpendicular from pin 1 and pin 1'.
Measure the length of both and compare the two distances.
Draw the normal to the mirror at both pin 2 positions.
Measure and compare angle of incidence, and the angle of reflection.

Answer the following questions on a separate sheet of paper.

1. State the Law of Reflection.

2. Is the reflection from your table regular or diffuse?

3. Make a drawing illustrating your answer to 2.

4. Is the reflection from the mirror regular or diffuse?

5. Make a drawing illustrating your answer to 4.

6. If you are using a mirror to look around a corner at someone, can they also see you?

Explain.

7. State some possible sources of error.