Physics 122 Weeks 9 & 10
Light Properties
Linear Light
Use the special FX "canned fog" to show that a laser beam is straight. (Also... who wouldn't want to play with fog and lasers???)
Pinhole Projector
A clear 500-watt light bulb is enclosed in a box with an iris diaphragm. Adjust the size of the iris to show image of the light bulb filament on the wall or ceiling. You may want to project this to your students using a document camera.
Reflection
Corner Reflectors
Multiple mirrors are set up to create a corner (2 that fold, or 3 at right angles) Use them to demonstrate the law of reflection off multiple surfaces, and introduce total internal reflection.
Law of Reflection
Using just a mirror and a laser you can introduce your students to the law of reflection.
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Collection of Mirrors
We have a large variety of mirrors in the demo room. Here are a few of the plane, convex, concave, confocal (mirage demo), Fresnel, and spherical mirrors available to you.
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Refraction
Simple Refraction
Darken your classroom and get the canned fog handy. Fog up the area, and shine the laser into the acrylic block. Then, slowly begin changing the incident angle!
Prism Dispersion
Place a high dispersion prism in front of a projector to disperse white light into the rainbow. You may need to rotate the prism a bit for best results, and remember that the rainbow will appear at an angle from the projected light.
Refraction Tank
Make sure that the tank is filled half full (not empty) with water in order to take advantage of the compass in the background. This is a great demonstration to support Snell's Law, investigate the critical angle, and demonstrate total internal reflection.
Water Refraction
A wooden dowel is placed half-way into a tank of water and observed.
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Disappearing Glass (Same "n")
When an object is placed in a medium with the same index of refraction it seems to disappear! Use this demonstration to help walk your students through the ray diagram of why this happens.
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Total Internal Reflection
Total Internal Reflectors
Here are some items that work as amazing total internal reflectors. Combine these with a document camera to allow your students to see where light reflects in each object.
TIR in a Beaker
Shine a laser on a glass beaker's lip such that the incident angle is almost 90 degrees. The beaker will light up as the laser light totally internally reflects!
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Lenses
Collection of Lenses
We have a large variety of lenses in the demo room. Here are a few examples of what you can find and use with your students.
Fresnel Lenses
These lenses are great for emphasizing that it is how light refracts through a medium that causes magnification and why a thin lens approximation can be a legitimate assumption.
The Shrinking Penny
This is a great "fun house" illusion. If you or your students have ever seen mirrors or windows that distort reality then you may have seen something like this.
Optics Kits
These are by far one of the most popular demonstrations when discussing ray optics. Some of our kits are magnetic, while others are designed to be used on a table top in tandem with a document camera.
Water as a Lens
When observing the ruler in this water filled cylinder the image appears farther away and magnified.
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Magnified Penny in Water
By placing the penny at the center of this water sphere it appears magnified. The image location and physical object are at the same location, but the magnification is about 1.3 times larger.
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