Higher

higher – lasers

by

The first laser was demonstrated in 1960 by Theodore Maiman and his research group at Hughes Aircraft Corporation† 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.

Screen shot 2013-04-18 at 19.26.22

 

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 🙁

eBook Download (2059)

higher – line spectra

by

We’ve looked at line spectra with spectroscopes and a spectrometer recently.  Now we’re considering 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.  Try it – the labels under the slider for photon energy match the electron transitions.

picture-3

You can read more about line spectra and their origin here.

The visible line spectrum of the Hydrogen atom is explained in this short animation. Click on the image below to start the clip.

While you’re watching the clip, try to explain why the video does not include ANY of the possible transistions back down to the ground state.

I’ve attached a pdf file with further notes on line spectra and the absorption/emission of photons.  Click on the link below to download your copy.

eBook Download (2477)

Higher – photoelectric effect

by

We looked at the photoelectric effect earlier this week.  This video has a similar demonstration to the gold leaf electroscope experiment I showed you in class and includes an explanation of the process.

Click on the picture below to download the simulation we used to investigate the effect of irradiance on frequency on photocurrent.  You’ll be prompted to install Java if you don’t have it already.

Once the animation is running, you can;

  • change the metal under investigation (we used zinc in class)
  • vary the wavelength of the incident light
  • vary the irradiance of the incident light.

Notice that below the theshold frequency you can’t get any photoelectrons, even if you set the light to its brightest setting.

Compare your results to the graphs provided in your notes.

I have attached some notes & questions on the photoelectric effect. Click on the link below to download a copy.

eBook Download (2378)

Higher unit 2 – solutions to practice NAB.

by

Here are my solutions to the practice NAB for Higher unit 2.

Check your own answers carefully.  Did you;

  • mix up the equation for charged particles with those for capacitors?
  • remember to calculate the period of an ac signal in seconds?
  • make the correct substitutions for V1 and V2 in the differential amplifier question?
  • use “it” instead of nouns in your explanations?
eBook Download (1707)

lasers are cool!

by

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.

Screen shot 2013-04-18 at 19.26.22

 

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 🙁

eBook Download (2059)

higher – where do line spectra come from?

by

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.

picture-3

You can read more about line spectra and where they come from here and here.

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.

eBook Download (2477)