Try this practice NAB if you are studying for a unit 2 resit next week. I’ll post answers over the weekend.
We’ve been looking at wave-particle duality this week.
Here are 2 videos. The first is about electron diffraction (G. Thomson’s experiment) and De Broglie’s equation, while the second looks at the Davisson-Germer experiment.
Following on from our discussion of the Davisson-Germer experiment, I found a copy of Davisson’s Nobel Lecture online. You can read it using the download link below. You should be able to follow Davisson’s lecture as it ties in nicely with the modern physics element of the AH course.
Sorry for the long wait! Here are worked solutions to the homework questions on calculus and special relativity. Come and see me if you want to go over any of them. Thanks.
Congratulations to Peter Higgs and Francois Englert on winning the 2013 Nobel Prize in Physics in recognition of their work on the particle we call the Higgs Boson. Here’s a video that may help to explain why this particle is so important to physicists.
We’ll spend the next two lessons in the library learning how to use Excel. Download the instructions using the link below. If you have your own LO3 data, feel free to work with those values instead of the numbers I have provided.
By the end of this activity you will be able to;
- manipulate raw data using formulae in cells
- plot a graph of your results
- add error bars to your graph
- add a line of best fit
- calculate the gradient and y-axis intercept of your line
Here are the solutions to the practice NAB for unit 3. How did you get on?
Here is a practice NAB for unit 3. Answers will follow shortly.
The first laser was demonstrated in 1960 by Theodore Maiman and his research group at Hughes† in California. Here is a good background article on the first laser, its inventor and the role that Einstein played in developing the theory of stimulated emission.
The principle of laser operation is outlined in this description of Maiman’s laser, which used a rod of polished ruby inside a spiral flashtube.
My favourite James Bond film, Goldfinger, has a scene where Sean Connery (the best 007 imho) is strapped to a table under a huge red laser. It should have been a saw but the invention of the laser, just 4 years earlier, was a gift for the writers. This scene helped the film win the best effects Oscar in 1965 and, more importantly, gave us the ultimate Bond quote:
Bond: Do you expect me to talk?
Goldfinger: No, Mr. Bond, I expect you to die.
Everyone should watch the laser scene.
Bonus points if you can tell me about the bad physics in that clip…
You can try running a laser for yourself. Click on the picture below to load a simulator. You’ll need Java on your computer to run the simulation.
Try changing lamp (pump) irradiance and mirror reflectivity on the single atom version before moving on to the multiple atom tab.
There are some pdf notes on lasers attached to the end of this post.
† Disclaimer: I used to work for Hughes before I trained as a physics teacher – the Glenrothes branch, not California
We looked at line spectra with a spectrometer before the holidays and this week we considered how these different colours of light are produced.
Here is a website that lets you choose the energy of a photon and see whether or not it causes a change in the energy of an electron inside the hydrogen atom.
The visible line spectrum of the Hydrogen atom is explained in the following short film. Click on the image below to start the clip.
I’ve attached a pdf file with further notes on line spectra and the absorption/emission of photons.