Year 9 Science
INTRODUCTION
The simple ideas of reflection which were studied in the previous
experiment will be extended. You will find out about the image formed
by a plane mirror.
REQUIREMENTS
Ray Box
6V Supply
c) Where does the image of the pencil appear to be?
Mounted Plane Mirror
Ray gate
• An image through which the rays of light pass is called a real image.
• An image through which the rays of light do not actually pass is called a
virtual image.
1. LATERAL INVERSION
d) What kind of image is formed in a plane mirror?
Place the mirror in the position shown and read the line of print below.
Look at the image of a few printed words in the plane mirror.
3. IMAGE OF A POINT
Position of mirror
a) Briefly describe the image. __________________________________
Place the mounted mirror on the blank page provided. Mark a point
"O" about 4cms in front of the plane mirror. This point can be
regarded as the object.
Direct a single ray of light from the ray box through "O" on to the
mirror (see diagram). Look along the reflected ray towards the mirror.
i)
ii)
Mirror
2. POSITION OF THE IMAGE
Hold a pencil about 30cms in front of the mirror.
towards the mirror and watch its image.
Move the pencil
Ray box
Move the pencil away from the mirror and watch the image of the pencil
in the mirror.
P
N1
M
Reflected
r i
rays
i r
Reflected
rays
Incident rays
a) What happens to the image? _________________________________
position 1
N2
position 2
Ray
box
a) Where does the image of the object appear to be?
b) What happens to the image?
08 Images in a Plane mirror Page 1 of 2
Repeat the experiment with the ray box in position 2 (see diagram).
Mark the position of the reflecting surface.
Remove the mirror and extend the two reflected rays back beyond the
mirror to meet in "P" (see diagram).
b) What is at "P"? _____________________________________________
c) Do these two rays of light really pass through "P"?
EXERCISES
1. Use your two conclusions for The image of a point to find the
position of the image of the letter “R".
a) What do you notice about the orientation (arrangement in
space) of the image?
b) What do you notice about the size and distance from the mirror
of the image compared with the object?
d) Is "P" a real or virtual image?
______________________________
Join "OP" and let it intersect the reflecting surface of "M". Measure the
perpendicular distances of "O" and "P" from the reflecting surface.
e) Record your observations. Measure the angle between "OP"
and the reflecting surface. Repeat the experiment several times.
Distance of "O" in
front of mirror
Distance of "P"
behind mirror
Angle between
"OP" & mirror
2. If you walk across a room at a speed of 3km/h towards a plane
mirror,
a) with what speed does your image move? _____________________
b) with what speed does your image approach you?
1
2
3
4
f) Form two conclusions from your table of results.
1: __________________________________________________________
__________________________________________________________
2: __________________________________________________________
__________________________________________________________
08 Images in a Plane mirror Page 2 of 2