Did you think of a question that could be studied, or make an observation
that was interesting or unexpected? You should send it to the Question
board!
Discuss some of these questions with the people in your group:
We do not recommend using a lens to try to start a fire. The little
spot of light is very bright -- too bright to look at, really. But
let's discuss the theory for a minute. All the light that hits the lens
is delivered to the image. If the image is smaller, the concentration of
the light is greater; if the lens is larger, more energy is collected. Thus
the relevant feature is the ratio of the diameter of the lens to the diameter
of the image. Then which of the lenses you have is the best for this
purpose, or are they all pretty much the same?
Although we should never look at the sun, sometimes we want to know what's
happening in that direction. For example, we would want to observe (somehow)
a partial solar eclipse; sometimes, too, there are visible sunspots, which are
regions on the face of the sun that are somewhat cooler than the rest. One way
to do this is to make an image of the sun on a screen, using a lens. If we want the image to
be big (so we can see the sunspots) and not too bright (so we can look at it), what
kind of lens do we need?
What does your sun viewer look like?
Louise's bridge party was a big success,
and now it's Margie's turn. Her idea is to write on the light bulbs
(like Louise did)
but use lenses to project the images on the ceiling.
Will this work at all? Will it work better? What kinds of things can
go wrong? I suspect Margie will need a lot of advice from an expert
like you.
Make a Model Camera (activity Lenses #8 in the manual). You have
several lenses to choose from, and there is a plastic lid in the kit that
will make a screen. You only need a box of the right size.
Please send
us your discussion of two of these questions (or a description of how you made
your model camera, and what you observed). Don't forget to tell us
who is in the group.
If there is something that you don't understand about images,
Ask
us! This is the end of this section.
Please note that these activities
are written up (in slightly different form) in the manual (in the
Lenses and Curved Mirrors sections).
The next section is about light energy.