Loading document…
Opening in Pages for Mac...
Your browser isn’t fully supported.
For the best Pages for iCloud experience, use a supported browser.
Learn More
Cancel
Continue
4.4 Wave behaviour
4. Oscillations and waves
Measuring the wavelength of laser light using a double-slit
Background
“
In modern physics, the double-slit experiment is a demonstration that light and matter can display
characteristics of both classically defi ned waves and particles; moreover, it displays the
fundamentally probabilistic nature of quantum mechanical phenomena. This type of experiment
was fi rst performed, using light, by Thomas Young in 1801, as a demonstration of the wave
behaviour
of light.
”
Source:
https://en.wikipedia.org/wiki/Double-slit_experiment
Experiment
: measuring the wavelength of laser light using a double-slit
Equipment
: laser, double slit, metre ruler, micrometer/callipers, white screen
Method
1.
Measure the distance between the two slits, the slit separation d and record here: _______ mm
2.
Place the double-slit fi ve metres away from a screen, this is the distance D.
3.
Shine the laser through the slit to the screen. There are different colour of light, try to use
different colours from other groups.
4.
Observe the interference pattern and measure the distance between the central bright fringe
and the 1st order fringe, s
5.
Repeat at different distances, D and measure s.
Table of results
You can choose to design your own table
Analysis
Plot a graph to determine the wavelength of the light used. The best way to do this would be to
plot a graph so the gradient is the wavelength.
Then calculate the gradient and hence the wavelength of light. Show this on your graph.
Compare this with any known value.
Explain any difference.
Distance between slit and screen, m
Fringe separation, s / m
Wavelength of light / m
4. Oscillations and waves
4.4 Wave behaviour
