AH Physics

the cloud chamber

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The cloud chamber has played a massive role in particle physics.  Saturated alcohol vapour in a container allows us to display the path of a particle, such as a muon, as it passes through the chamber.  The video below shows the kind of trails that a cloud chamber will produce.

Cloud chamber from momo on Vimeo

I’m posting about the cloud chamber after reading an article in Scotland on Sunday about its inventor,  CTR Wilson – winner of the 1927 Nobel Prize for Physics.  I didn’t know Wilson was Scottish and I didn’t know that his research was inspired by the cloud observations he performed while posted to the Highlands, Ben Nevis to be precise.

He’s not the only particle physicist to have found inspiration in our back yard.  Peter Higgs, of Higgs boson fame, came up with his theory to explain the source of mass during a Highland holiday.

Using excel for AH Physics investigation graphs

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We spent some time today looking at ways of analysing data obtained from your investigation experiments. It is often a good idea to generate a graph of your results.  Your graph does not have to be drawn by hand, it can be produced on a spreadsheet.  If you do decide to use a spreadsheet, remember to print the gridlines on your final version of the graph.

If you use Excel, there is a function called linest that can be used to determine the gradient of the best-fit line and the intercept with the y-axis.  If you follow the instructions below, the linest function will also calculate the uncertainty in the gradient and intercept point for you.

Here is a linest tutorial to get you started.  It also includes instructions on how to add custom error bars to your graph.

Excel Tutorial: Using LINEST function, Plotting a graph, Adding Error Bars

I have included a pdf of a different help sheet – download it using the link at the end of this post.

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uncertainties booklet

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It’s time to start looking at the uncertainties in your investigation results.  I have attached a pdf of a guide to uncertainties in AH Physics.  You should pay particular attention to the sections on combining uncertainties and analysing graphs.

I will post additional resources to help you deal with uncertainties in your graph.

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