In a message dated 5/7/02 10:36:10 AM, herbgottlieb@JUNO.COM writes:
<< > Try shining a laser pointer on the real image. Ask students why
something you can't touch seems to reflect light.
If the student comes up with a plausable response,
how does the teacher know if it is correct???
Herb Gottlieb from New York City >>
The key word is "seems" to reflect light. As pointed out earlier, the laser
light must enter the cavity between the two concave mirrors, so hold the
laser pointer above the apparatus and shine it downward (slight angles don't
matter). Light passing through the image location in this way will end up on
the object (light ray reversal). Now you have an object with a little circle
of laser light on it, which becomes an image, with an apparent little circle
of light on it. I first saw this phenomenon in an exhibit in the Toronto
Science Museum--an image of a spring which "seemed" to reflect light from a
flash light.