Velocity of Light - P41 Version

[Description] [Equipment] [Write-up] [Circuit Diagrams]

Description | Top

The students measure the velocity of light by two totally different methods:

a. Electrical measurement of the resonant frequency of an LC circuit. The inductance L and capacitance C of a simple circuit are calculated from their dimensions by standard electromagnetic theory, and e_om_o calculated from the product LC , which can be found by measuring the resonant frequency of the LC circuit.

b. Direct measurement of the velocity of propagation of a light wave emitted by a laser diode. This is done by emitting a light wave which is amplitude- modulated at a high frequency and measuring the phase change of the modulation as a function of distance.

Equipment | Top

Electrical Measurement Apparatus



Time of Flight Apparatus



Time of Flight Apparatus

(Number of setups: 1)

Part I - Time of Flight

1 HP 56400A oscilloscope
1 HP 8601A generator/sweeper
1 Simpson multimeter
1 12V DC power supply
1 10 dB amplifier/diode current adjustment
1 directional coupler
1 T-bias
1 diode laser/mounting apparatus
1 photodetector/mounting apparatus
1 retroreflector/mounting block and optical bench mount
1 1.5 optical bench mounted on a wooden board
1 lens
8 BNC cables (one cable with banana jacks on the end)
1 water filled tube with two optical bench mounts

Part I - LC Circuit

1 HP 56400A oscilloscope
1 Philips PM6666 frequency counter
1 HP 209A oscillator
1 coil inductor (mounted on a plywood board)
1 concentric cylinder capacitor (mounted on a plywood board)
2 alligator clips
3 BNC cables
2 BNC to banana (male) adaptors
1 BNC to banana (female) adaptors
1 BNC bullet (straight) connector
2 small diameter loops of wire for coupling to system

Circuit Diagrams | Top