Up

 

                                                

 

Rogue Physicist.  Free resources for physics education © 2006-2016 Dorian Pascoe.  Email: dorian.pascoe@hotmail.co.uk

Most resources are available under a Creative Commons Licence.  Visit our mirror at www.physicsweb.altervista.org

 

 

AS Unit G492 - Understanding Processes

Chapter 7 - Quantum Behaviour
Title

Description

Task 1 - Lumpy light...

 Your teacher will show you this presentation, and explain the implications for our wave model of light...

Task 1b - Light as a particle

 Our new ideas about the model of light requires us to think about some key conepts in a slightly different way.  Your teacher will ask you to share your ideas about how to define the following properties for a photon:

• frequency

• wavelength

• amplitude

Task 2a - Light as a particle

We need to be able to calculate the energy carried by a photon, and also to calculate the number of rotations a photon undergoes along  a given path, in order to find the phase of the photon when it arrives at its destination.  These notes help explain how to do this.  When you are happy you understand, answer the questions at the bottom of each page.

Task 2b - Light as a particle

 Answer these questions (Q20E), which look at the energy carried by a photon and the number of photons emitted from a source, and these questions (Q10S) which look at the number of rotations a photon undergoes whilst travelling along a path.
Task 3 - A quantum view of diffraction... Lets think about the double slit experiment we looked at recently.  We need to be able to explain the pattern we observe in terms of the interaction between the "particles" (photons) of light.  We should surely see something like this - but we know this is not the case!

Let's consider slowing the stream of light down, until there is only one photon travelling through at a time, and see how this affects our ideas...  Your teacher will explain to you a rather surprising conclusion we draw from our observations...!
Task 4a - Many paths... Look at this simulation, which shows how the different paths followed by a photon affect the probability of arrival.
Task 4b - Many paths... Suggested exam questions:

June 08 Q11 - last section (2 marks)

June 09 Q5 (Section A, 3 marks)
Task X A
Task X A
Task X A
Finding Planck's constant 1. Remind the person next to you:

        • what the current-voltage graph looks like for a diode.

        • The regions of the EM spectrum, in order.

        • The regions of the visible spectrum, in order.

2. Your teacher will explain how our quantum model of light requires us to look at an LED in a slightly different way.  Measure the striking voltage for each of the LEDs in the array.  Record your results in a table.

3.  Stick these notes in your exercise book, next to your results, and follow the instructions to find Planck's constant.

Suggested exam question:

June 09
LED as a quantum system Suggested exam question(s):

June 09 Q9 (Section B, 11 marks)
   
The Photoelectric effect The photoelectric effect is an important piece of evidence which supports the photon model of light.  Your teacher will show you this simulation, and explain why the effect cannot be accounted for using the wave model.

When you are happy you understand, try completing this comprehension exercise (Q50C).
   
   
Double slit experiment for electrons Look at this website.
The Structure of the Atom Read about how Rutherford's famous alpha-scattering experiment helped us to develop our primitive nuclear model of the structure of the atom.
Rutherford Scattering

See a simulation of Rutherford Scattering (alternative link here)
Models of the Hydrogen Atom

Look at different models of the Hydrogen atom have evolved, from the Thomson's simple plum pudding model, to the accepted quantum model we use today.
Atomic Ionisation and Excitation - Gas Discharge Lamps

A simulation to show how Fluorescent Lights / Gas Discharge Lamps work. 

Atomic Ionisation and Excitation

Learn about the atomic processes behind absorption and emission spectra with this presentation.
  Quantum Wave Interference (java)
The Photoelectric Effect The Photoelectric Effect (java)
Blackbody Radiation This simulation shows the intensity of radiation as a function of frequency for a perfect 'black body'.  The idea of black body radiation was influential in the development of the quantum (photon-based) model of light.
Electron Spin This simulation illustrates the Stern-Gerlach experiment, an example of the strange property of electron 'spin'.