*** CLASS SET – DO NOT WRITE ON ME!!! ***
PLANE MIRRORS AND CONVEX LENSES – LAB
PLANE MIRRORS – The Law of Reflection
 Set up the mirror and toys as shown on the board. Use a straightedge for all lines!!!
 Mark the location of the mirror (line across the paper) and each of the toys (dots).
 Take the figures and the mirror off of the paper.
 Measure the distance from the mirror to the location of each of the two toys.
 For each toy, put a dot the same distance away from the mirror line on the opposite.
These dots represent the reflection for each figure.
 Connect the dots from one of the real toys to the reflection of the other toy. Do this for
both toys. Make your lines solid in front of the mirror and dashed behind it.
 Using a protractor, measure the angle of incidence and angle of reflection. Remember to
measure from the normal! Record them on your paper.
 Put the mirror back on the paper where you marked it. Check your work with a laser – lay
the laser down on the paper so light is being emitted at the same location as the dot for
one toy. The laser should hit the mirror at the same point that your rays intersect the
mirror.
 Make a “screen” out of a scrap of paper. Place it on the dot of the second object.
Observe the laser beam.
 Answer the following questions on your own paper.
1) What did you observe about the reflection and the lines you drew when you put the
mirror and the figures back on the paper?
2) What is the law of reflection?
3) How did this lab demonstrate the law of reflection?
4) Are the reflections real or virtual images? How do you know?
CONVEX LENSES – Image Formation
*** Be VERY careful with the lenses – they pop out of their holders VERY easily!!!***
Part I - Magnification
 Hold a lens above the picture to the right.
 Move the lens away from the paper until the moment you no longer see a clear
image (when the image starts to become distorted or fuzzy). You may need to
do this with your paper on the floor.
*** CLASS SET – DO NOT WRITE ON ME!!! ***
 Measure the distance from your paper to the lens, and record.
 Answer the following questions on your own paper.
5) What happens to the size of the image as you move the lens away from the paper?
6) What type of image are you looking at through the lens, real or virtual? How do you
know?
Part II – Image Formation on a Screen
 Place a light bulb at the “zero” end of the meterstick, so that the middle of the bulb is at
the end of the meterstick.
 Place a lens along the meterstick, and hold a piece of paper vertically at the end of the
meterstick.
 Turn on the light. Move the lens back and forth until you see a clear image of the
lightbulb on the paper screen you are holding.
 Measure and record the distance from the lightbulb to the center of the lens (d o) and the
distance from the center of the lens to the image (di).
 Answer the following questions on your own paper.
7) What is the focal length of your lens? (HINT: Use the Lens Equation to figure this out.)
8) What type of image formed on the screen, real or virtual? How do you know?
9) How does this distance you measured in Part I compare to the focal length you
calculated for Part II?