Curved Mirror Discovery
In steps 1 through 4 make sure the mirror is positioned so that the middle beam reflects back on itself.
1) Use the 3 beam ray box. What happens when beams hit a reflecting surface that curves towards the
light source? Show the path of the reflected light on the diagram below. Change the angle of the ray
box. What do you notice? This is called a concave mirror.
2) Using the single beam ray box and a concave reflecting surface, shine the beam on each path shown
below. Trace the path of the reflected light. What do you notice about all of the reflected beams?
3) Use the 3 beam ray box. What happens when beams hit a reflecting surface that curves away from
the light source? Show the path of the reflected light on the diagram below. Change the angle of the
ray box. What do you notice? This is called a convex mirror.
4) Using the single beam ray box and a convex reflecting surface, shine the beam on each path shown
below. Trace the path of the reflected light. What do you notice about all of the reflected beams (hint:
extend the reflected rays behind the mirror)?
For the rest of the step use the double sided reflectors. The side that would hold water is the concave
side.
5) Go near the window and use the concave side of the mirror to focus the image of an object that is a
long way from the school on the white card. Measure the distance from the mirror to the card with a
ruler. What are the characteristics of this image?
6) Set the mirror on your desk with the concave side up. Hold a pencil closer to the mirror that the
distance you measured in step 5. Look at the image making sure you can see the tip of the pencil and
are looking from straight above. What are the characteristics of this image?
7) Keep the mirror on your desk with the concave side up. Hold a pencil a distance of about 3 cm more
than the distance you measured in step 5 from the mirror. Look at the image making sure you can see
the tip of the pencil and are looking from straight above. What are the characteristics of this image?
8) Keep the mirror on your desk with the concave side up. Hold a pencil right at the mirror. Look at the
image making sure you can see the tip of the pencil and are looking from straight above. Watch the
image carefully and slowly move the pencil away from the mirror. Describe how the image of the pencil
changes as the pencil gets further away from the mirror. Is there a time when there is no image?
9) Flip the mirror so that the convex side is up. Hold a pencil right at the mirror. Look at the image
making sure you can see the tip of the pencil and are looking from straight above. Watch the image
carefully and slowly move the pencil away from the mirror. Describe the characteristics of the image.
Do they change like they did in step 8?