Speed of Light Kit
The transmitter contains a high intensity LED pulsed at 1MHz and provides a synchronisation pulse to the “ext.sync” sockets of the oscilloscope. The light pulse travels are displayed as ‘Y1’ on the oscilloscope. The light pulses travel to the receiver, where its signal is displayed as ‘Y2’. The experiment is performed twice, once with the transmitter and receiver directly aligned 1 metre apart, the second time with the pulses travelling across the laboratory to the mirror and being reflected back.
By measuring the difference in the position of the Y2 trace in the two cases the time (typically 0.1μs) for the return journey across the laboratory (typically 30m) the speed of light can be calculated.
• Now supplied in a Gratnells tray
• Unique kit for the measurement of ‘c’ directly, within the dimensions of a science laboratory
• Simple to understand method
• Comparison of ‘c’ in air with that in the plastic of a fibre optic cable for direct calculation of refractive index.
The apparatus consists of a transmitter and receiver, two Frensel lenses with holders, a mirror, plug-top power supply, all connecting leads and instruction booklet.
A double-beam oscilloscope is required which has an external trigger, a bandwidth of at least 20MHz and time-base with a resolution of 20ns per division.