TOPIC:

ID Code: K8-04
Purpose: Measure the speed of light
Description: A laser light pulse a few nanoseconds long is emitted by a light-emitting diode and immediately strikes a partially silvered mirror. The reflected light returns to a phototransistor to give the first pulse of the oscilloscope trace shown in the picture. The light transmitted through the partially silvered mirror reflects off a distant front-surface mirror, in the foreground of the picture, returning to the phototransistor to create the second pulse. The distance the laser beam travels, measured using a metric tape, and the elapsed time, determined from the oscilloscope trace, are used to calculate the speed of light.

Please Note: Care must be used to position the light reflected from the distant mirror onto the phototransistor.

Availability: Available