Hold the convex mirror in front of you. Move the mirror toward
and away from you and observe the image formed. Hold a plane
mirror in front of you. Move it toward and away from you to
observe the image formed. Hold the concave mirror in front of you.
Move it toward and away from you and observe the images formed.
Compare the images with respect to size and orientation.
Measure the focal length of the concave mirror by focusing the
sun's image on an index card. Reflect the sun's rays onto the card
and move the mirror toward and away from the index card until a
small dot is focused. Measure the straight-line distance from the
card to the center of the mirror. This is the focal distance of
the mirror, and the image is located at the focal point. (DO NOT
LOOK DIRECTLY AT THE SUN OR FOCUS THE SUNLIGHT ON YOURSELF OR ANY
Figure 2: One possible arrangement
of the candle, mirror, and index card for examining real
Place a lit birthday candle mounted in modeling clay on a lab
table. Hold the concave mirror a distance equal to the focal
length from the candle. Dim the room's lights and hold the index
card away from the mirror and candle to view the reflected light
(figure 2). Compare the amount of light reaching the card when the
mirror is in position and reflecting the candlelight to when there
is no reflection of light and the candle sheds only direct light
on the card.
Position the mirror so it is at a distance twice that of the
focal length from the candle. Place the index card at a distance
near the focal length from the mirror and move it towards and away
from the mirror until an image of the flame forms on the index
card. The image will be inverted. Continue to vary the distances
among the candle, screen, and mirror to investigate the images