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# 9.3. Interference

Here we bring together all of the different ideas related to waves, interference and refraction to ook at a few specific examples. Firstly we look at diffraction gratings - which are commonly used to analyse light spectra. Finally we look at the phenomenon of thin film interference - the reason behind why bubbles and oil slicks have their characteristic rainbow sheen. There is some really interesting physics behind this, though it requires you to be confident using ideas about reflection, refraction and phase shift.

Before we start, take a look at this video by Crash Course

The section has been divded up as follows:

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Multiple Slits

## Video Lessons

 Chris Doner Double Slit Recap Multiple Slit Interference IB Specific

## Resources

 IB Physics Topic 9 Notes IB-Physics.net Chapter 9 Summary IB Revision Notes Mr. G 9.3 Teaching Notes 9.3 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 9.3 (Interference) MCQ Topic 9 (Waves) End Quiz Quick IB Specific Mixed MCQs Mr. G 9.3 Formative Assessment Topic 9 Summary Qs IB Specific Questions Physics and Maths Tutor Interference (AQA 2) Interference MS (AQA 2) A-Level Qs: overlapping content
Diffraction Gratings

## Video Lessons

 Khan Academy Diffraction Gratings Physics Online Diffraction Gratings Science Shorts Diffraction Gratings

## Resources

 IB Physics Topic 9 Notes IB-Physics.net Chapter 9 Summary IB Revision Notes Isaac Physics Diffraction Gratings Level 6 Beyond IB Mr. G 9.3 Teaching Notes 9.3 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 9.3 (Interference) MCQ Topic 9 (Waves) End Quiz Quick IB Specific Mixed MCQs Isaac Physics Interference Mr. G 9.3 Formative Assessment Topic 9 Summary Qs IB Specific Questions Physics and Maths Tutor Interference (AQA 2) Interference MS (AQA 2) A-Level Qs: overlapping content
Thin Film Interference

#### Thin Film Interference

Here we draw all these ideas we have looked at in our study of waves and wave behaviour to look at one specific example - why do bubbles or oil slicks appear to show rainbow patterns across their surface? This is all due to something called thin film interference, and it requires us to use our understanding of phase shift, reflection, wave interference, refraction and Snell's law to get our heads around it.

## Video Lessons

 Chris Doner Thin Film Interference IB Specific Khan Academy Thin Film Interference 1 Thin Film Interference 2

## Resources

 IB Physics Topic 9 Notes IB-Physics.net Chapter 9 Summary IB Revision Notes Mr. G 9.3 Teaching Notes 9.3 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 9.3 (Interference) MCQ Topic 9 (Waves) End Quiz Quick IB Specific Mixed MCQs Mr. G 9.3 Formative Assessment Topic 9 Summary Qs IB Specific Questions