'camera', you will need:
2 elastic bands
a pin or tack
a few sheets of black sugar paper.
one end of the roll with foil.
Stretch the foil tight and fasten it with an elastic band.
Cover the other end in a similar way with grease-proof or tracing paper.
Make a pin-hole in the centre of the foil end, using the tack or pin.
There must be no more than a pin-hole. If you tear the foil, replace it
and try again.
be using this device to view a candle/night-light flame.
If you would prefer not to use a naked flame, you could cut a triangle,
with sides about 4 cm. long, from thick card, and hold it in front of a
this should be done in a darkened room. If this isn't possible, you may
have to wrap your camera tightly in a tube of black sugar paper and look
down the dark tube to see a clearer image. Make sure that you leave the
foil end sticking out.
foil end near the flame and look at the other end of your camera.
Adjust position until a clear image of the flame is formed on the grease-proof
will notice that the image is upside-down.
diagram which accompanies these notes illustrates why.
are looking at when you use the camera is not the flame itself but an image
of the flame which has been formed on the screen.
flame is emitting light in all directions but the only way in which light
can get from the flame to the screen is to go through the pinhole.
the image upside-down?
at the diagram and notice the angle at which light from the top of the
flame enters the hole.
doesn't change direction but goes on to strike the bottom of the screen.
light from the bottom of the flame ends up at the top of the screen.
pupils the activity sheet and see whether they can figure out what's happening.
They might also look towards the classroom windows and see what images
are formed on the screen.