9.5. Doppler Effect
We have all hear the Doppler effect in action when standing next to fast moving traffic. It is the NEEEEEEEEEOOOOOOOOOOW (spelling?) noise a car or motorcycle makes when it drives past you at speed. There are a million videos demonstrating this effect on YouTube - I like this one as he demonstrates it whilst playing Careless Whisper.
In this section we look at some of the maths behind Doppler shift. Given the speed of the source and/ or observer we will learn how to calculate the perceived increase or decrease in frequecy. We will also look at Doppler shift of electromagnetic waves - otherwise known as red shift. The section has been divided up as follows:
​
-
The Doppler Effect - Introduction to the Doppler effect and what causes it
-
Moving Source/ Observer - bringing in some of the maths behind Doppler
-
Electromagnetic Doppler shift - looking at the expansion of the universe through using Doppler shift.
The Doppler Effect
Video Lessons
Chris Doner | Doppler Effect | IB Specific | ||||
Khan Academy | Intrroduction to Doppler | Doppler Equation | ||||
Physics Online | Doppler Effect |
Resources
IB Physics | Topic 9 Notes | |||||
IB-Physics.net | Chapter 9 Summary | IB Revision Notes | ||||
Isaac Physics | Doppler Effect | Level 4 Beyond IB | ||||
Mr. G | 9.5 Teaching Notes | 9.5 Student Notes |
Questions
Cambridge University Press | Topic 9: Add Qs | Topic 9: Add Qs MS | Topic 9: MCQs | CUP Website Link | Freely available online | |
Dr French's Eclecticon | Interference, Doppler, Polarisation | Interference, Doppler, Polarisation Solutions | Link to Dr French's Site | Extension: Pre-University Material | ||
Grade Gorilla | 9.5 (Doppler) MCQ | Topic 9 (Waves) End Quiz | Quick IB Specific Mixed MCQs | |||
Mr. G | 9.5 Formative Assessment | Topic 9 Summary Qs | IB Specific Questions |
Moving Source and Moving Observer
The follow simulation by Geogebra allows you to change the source and observer velocity and determine the effect on the perceived frequency. Write out the two equations, and make sure you are confident in each case whether to use a '+' or '-' sign.
Video Lessons
Chris Doner | Moving Source/ Observer | IB Specific | ||||
Khan Academy | Moving Source | Reflection (Double Doppler) |
Resources
IB Physics | Topic 9 Notes | |||||
IB-Physics.net | Chapter 9 Summary | IB Revision Notes | ||||
Isaac Physics | Doppler in 1D | Level 4 Beyond IB | ||||
Mr. G | 9.5 Teaching Notes | 9.5 Student Notes |
Questions
Cambridge University Press | Topic 9: Add Qs | Topic 9: Add Qs MS | Topic 9: MCQs | CUP Website Link | Freely available online | |
Grade Gorilla | 9.5 (Doppler) MCQ | Topic 9 (Waves) End Quiz | Quick IB Specific Mixed MCQs | |||
Mr. G | 9.5 Formative Assessment | Topic 9 Summary Qs | IB Specific Questions |
Doppler with Electromagnetic Waves
Video Lessons
Chris Doner | EM Doppler | IB Specific | ||||
Khan Academy | Red Shift Intro |
Resources
IB Physics | Topic 9 Notes | |||||
IB-Physics.net | Chapter 9 Summary | IB Revision Notes | ||||
Isaac Physics | Doppler EM | Level 4 Beyond IB | ||||
Mr. G | 9.5 Teaching Notes | 9.5 Student Notes |
Questions
Cambridge University Press | Topic 9: Add Qs | Topic 9: Add Qs MS | Topic 9: MCQs | CUP Website Link | Freely available online | |
Dr French's Eclecticon | Interference, Doppler, Polarisation | Interference, Doppler, Polarisation Solutions | Link to Dr French's Site | Extension: Pre-University Material | ||
Grade Gorilla | 9.5 (Doppler) MCQ | Topic 9 (Waves) End Quiz | Quick IB Specific Mixed MCQs | |||
Isaac Physics | Red Shift | Hubbles law not relevant | ||||
Mr. G | 9.5 Formative Assessment | Topic 9 Summary Qs | IB Specific Questions |
... and another little Physics joke to finish - DrR
"A cop pulls over a physicist for running a red light. The physicist tells the cop that from his point of view, the light was green, not red. So the cop gives him a speeding ticket."
Additional Resources
IB Questions
A question by question breakdown of the IB papers by year is shown below to allow you to filter questions by topic. Hopefully you have access to many of these papers through your school system. If available, there may be some links to online sources of questions, though please be patient if the links are broken! (DrR: If you do find some broken links, please contact me through the site)
Questions on this topic (Section 9) are shown in royal blue.
Use this grid to practice past IB questions topic by topic. You can see from the colours how similar the question topic breakdown is year by year. The more you can familiarise yourself with the IB question style the better - eventually you will come to spot those tricks and types of questions that reappear each year.