PURPOSE: To demonstrate frustrated total internal reflection using microwaves.
DESCRIPTION: A beam of 12cm microwaves reflects internally on the hypotenuse of a right angle paraffin prism. Bringing the hypotenuse of a second identical paraffin prism within a few cm of the first prism allows the wave to be transmitted straight through the two prisms.
The microwave sensing antenna can be located at the position of the internally reflected ray to show that this ray disappears when the second prism is moved close. Alternatively, the antenna can be located in the straight through direction to show that waves continue in a straight line when frustrated total internal reflection occurs.
REFERENCES: (PIRA unknown.) See Demonstration Reference File for further information on this demonstration.
EQUIPMENT: Microwave source, two identical paraffin right angle prisms, and receiver with overhead projector meter on overhead projector.
SETUP TIME: 5 min.
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