Physics Demo Number: 090

Approximate Run Time: 10 min

Smoke Box Elements To Show Live Ray Diagrams For Lenses

Demo Description

A smoke-filled box with two lenses inside used to see the ray paths of five parallel laser beams.

The laser ray box (used to provide the beams for the smoke chambers) can be used more simply with the magnetic cards and plastic optical elements that came with  the box.

    Scientific Principles

  • Ray tracing for diverging and converging lenses

  • Red Laser Light is Preferentially Scattered in the Forward Direction by Smoke Particles

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Equipment

  • Wood base

  • Laser Ray Box, lenses and incense burners

  • Lab Jack

  • Two smoke box sections

  • Original plastic elements with magnetic backing to stick to board or to ray diagram cards.

Equipment Location

  • Wood base is on [C-3-3].

  • Laser Ray Box, lenses and incense burners are in Kit (090) on [C-3-3] .

  • Lab Jack is on [G-1-6].

  • The two smoke box end- sections live on [C-3-2] and [C-3-3].

  • Original plastic element accessories on [C-2-1]

Instructions:

Photo 1 shows the smoke box (two pieces) set up (thanks to Science Shop machining expertise) with a positive and a negative lens in nice metal holders.

A close-up of the Laser Ray Box and its battery power supply is seen in the second photo.
The third photo shows a close up of the lenses. One needs to set the smoke box on a lecture cart and rotate the cart so that students can view the laser light as it is moving towards them.

Photos 4 and 5 are taken from the students' viewpoint and show the result of the five parallel beams from the Laser Box  coming through first the positive lens and then the negative lens.

The last three photos  show smoke free possibilities.


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5

  

















The  laser ray box came as part of a'Black  Board Optics'- type  kit for showing  ray diagrams without the aid of smoke boxes. The plastic lenses and other components of that kit are in its box on [C-1-5].

The last two photos show one of the intended modes of use  with a sheet of paper substituted for the document camera.

One may also secure all the elements of Black Board Optics kit to the lecture hall chalk boards by using the magnetic strips affixed to the back of each component and making use of the scattering properties of the chalk residue to view the detailed path of the rays on the board's  surface.
Writeup created by David A. Burba
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