Re: [Phys-l] [tap-l] pinhole camera

[Hugh Haskell <hhaskell@mindspring.com>]

At 14:01  -0400 4/12/07, Richard Heckathorn wrote:
> Mount a clear filament light bulb (mine has a
> c-shape filament when looking down from the top)
> to the bottom of a cardboard box. I have a lamp
> socket that I use that has the cord coming out the
> socket with a push-on push-off switch on the
> outside. I then cover the other side of the box
> with aluminum foil. In addition, I mounted a nut
> to one side of the box so that I can hold it up
> with a tripod.
>
> With the light on and the foil side pointed toward
> the chalk board, take a pin and punch on hole at a
> time in the foil.
Dick's suggestion is excellent, and it doesn't require a super-dark 
room to work. I have had a device like that for many years. A hole 
punched in the foil cover sends an image of the filament of the light 
bulb onto the ceiling or wall. After showing them the effect of 
punching a hole in the foil, I then punch several holes--maybe 10 or 
so--each one of which puts an image of the filament on the ceiling or 
wall.

Then I have a large magnifying glass lens--maybe 6 inches in 
diameter, and when I hold the lens over the collection of holes, and 
position it just right, it puts all the images into one location. It 
makes a very compelling introduction into just what lenses do.

Hugh
--

************************************************************
Hugh Haskell
<mailto:haskell@ncssm.edu>
<mailto:hhaskell@mindspring.com>

(919) 467-7610

Hard work often pays off after time. But Laziness always pays off now.

			February tagline on 2007 Demotivator's Calendar