We’ve been looking at the photoelectric effect this week. In this video, Professor Dave reviews some of the points we covered in class.
Click on the picture below to download a simulation 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.
We’ve been looking at Einstein’s special theory of relativity this week. Special relativity is tricky get get your head round. Let’s start with a video about the speed of light.
We watched this video in class, it follows Einstein’s thought process as he worked through his special theory of relativity.
another take on special relativity and the twins paradox
…and the Glesga Physics version
length contraction
This video has helpful examples to explain length contraction.
Sometimes it’s easier to imagine we’re a stationary observer watching a fast moving object go whizzing past. For other situations, it’s better to put yourself into the same frame of reference as the moving object, so that everything else appears to be moving quickly, while you sit still. The muon example in this video shows how an alternative perspective can work to our advantage in special relativity.
Another way to think about this alternative frame of reference is that it’s hard to measure distances when you yourself are moving really quickly. Think about it, you’d get tangled up in your measuring tape like an Andrex puppy.
It would be far easier to imagine you’re the one sitting still and all the objects are moving relative to your position, as if your train is stationary and it’s everything outside that’s moving. That keeps everything nice and tidy – including your measuring tape. Got to love Einstein’s postulates of special relativity.
I’ve marked your HW jotters and will hand them back during tomorrow’s lesson.
I’ll go over the main issues in class but many of you need to review the way you attempt tension questions; use a free body diagram and only use F=ma when you know the resultant force. These two videos should help.
Your assignment will be based on an optoelectronics topic. You will get some ideas for practical work by downloading this booklet.
I have attached a copy of the Scholar notes for unit 3 of the CfE Higher course. You will find background physics with appropriate energy band explanations on pages 103-142.
Thanks to Mr Ferguson for sharing his copy of the marking instructions for the 1996 Higher paper, it’s the only one I didn’t have! You’ll find a link to his answers on the Higher revision page.
