1. Wave Interactions Reflection Absorption Refraction Diffraction
Law of Reflection
Total Internal Reflection
Absorption
Refraction
Diffraction
Interference
Constructive
Destructive
Standing Waves
Polarization
Resonance

2. Wave Interactions

3. Anechoic Chamber
An anechoic chamber ("an-echoic" meaning non-reflective, non-echoing or echo-free) is a room designed to completely absorb reflections of either sound or electromagnetic waves. They are also insulated from exterior sources of noise.

4. Wave Interactions
The law of reflection states that the angle of incidence is equal to the angle of reflection.

5. Wave Interactions

6. Wave Interactions

7. STOP! Check for Understanding
What is the difference between reflection and refraction?
Provide an example of each.

8. Wave Interactions

9. Wave Interactions – Interference
When two or more waves are at the same place at the same time, the resulting effect is called interference.
Waves overlap to form an interference pattern.
The waves combine to form a single wave.
Constructive interference - when the crest of one wave overlaps the crest of another, their individual effects add together. The result is a wave of increased amplitude.
Destructive interference – when the crest of one wave overlaps the trough of another, their individual effects are reduced. The result is a wave of decreased amplitude.

10. What happens when two crests reach a boat at the same time?
The boat rises HIGHER.
What happens when two troughs reach a boat at the same time?
The boat sinks LOWER.
What happens when one crest and one trough reach a boat at the same time?
NOTHING!
The crest and trough cancel out.

11. Check for Understanding
What is interference?
Is interference always a bad thing?

12. Polarization Polarization is the alignment of transverse waves.
Polarizing light filters affect light waves the way the fence affects the waves in the rope.

13. Standing Waves
Although waves usually travel, it is possible to make a wave stay in one place.
A wave that is trapped in one spot is called a standing wave.
Standing waves are the result of interference. The resultant wave is created by the interference of two waves traveling at the same frequency, amplitude and wavelength but in opposite directions.

14. Standing Waves In a standing wave, the nodes remain stationary.
Antinodes occur halfway between nodes.
The largest amplitudes areas are know as antinodes.
Standing waves
strings of musical instruments,
by blowing across the top of a soda bottle.

15. Nodal Lines
A nodal line is a line of minimum amplitude in a moving wave.
When 2 waves of similar wavelength meet, and are not in phase, interference lines occur.

16. Nodal Lines

17. Interference and Light
Interference and diffraction of light support that light is a wave. This means that light waves create anti-nodal lines and nodal lines when light waves interact.

18. Interference and Light

19. The Doppler Effect
The Doppler effect is the change in observed frequency due to the motion of the source or observer.
The Doppler effect is the frequency shift that is the result of relative motion between the source of waves and an observer.
Higher frequency: Object approaching
Lower frequency: Object receding

20. The Doppler Effect
Example: As the sound of a car's horn passes and recedes from you, the pitch of the horn seems to decrease.
Some application:
Echolocation (e.g., Submarines, Dolphins, Bats, etc.)
Police Radar
Weather Tracking

21. The Doppler Effect
MOVING
SOUND-GENERATING OBJECT
STATIONARY
SOUND-GENERATING OBJECT
Velocity, v A B
Waves are created at point source and radiate outward creating a wave front with the same frequency as that of the source. Wavelengths stay the same
As a an object moves towards you the sound waves compress.
As an object moves away from you the sound waves lengthen

22. Scattering Light scattering
Occurs when light hits an object with an uneven surface
When this happens light is reflected in all directions

23. Scattering Why is the sky blue? Why are clouds white?
This is due to blue wavelengths of light being scatted by the most by the atmosphere as they are the shortest wavelength.
Why are clouds white?
This is due to the large molecule of water in the clouds scattering all wavelength of light

24. Scattering

25. Electromagnetic Spectrum
Light is a transverse wave as it can be polarized
Light is a wave as diffraction & interference occur in light.
Electromagnetic waves do not require a medium.
Currently we recognize that there are different types of electromagnetic waves.

26. Electromagnetic Spectrum
The range of wavelength for visible light are 7 x 10-7 m to 4 x 10-7 m

27. Shadows and Images
Shadows and images are produced because light travels in straight lines.
If a light source is close to an object it produces a clear shadow.

28. Shadows and Images
When a light source is further away from an object it produces a partial and full shadow.
Penumbra is a partial shadow
Umbra is a full shadow

30. Penumbra and Umbra
Solar and Lunar eclipses have a Penumbra and an Umbra
Although, Penumbras exist in real life it is easier to consider mathematical examples using sharp shadows that do not have a penumbra.

31. Pinhole camera Image produced is Inverted (upside down)
Real (can be projected onto a screen)
Usually smaller

32. Pinhole camera

33. Pinhole camera

34. Pinhole camera
𝑚𝑎𝑔𝑛𝑖𝑓𝑖𝑐𝑎𝑡𝑖𝑜𝑛= ℎ𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑖𝑚𝑎𝑔𝑒 ℎ𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑜𝑏𝑗𝑒𝑐𝑡 = ℎ 𝑖 ℎ 𝑜 OR
= 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑜𝑓 𝑖𝑚𝑎𝑔𝑒 𝑓𝑟𝑜𝑚 ℎ𝑜𝑙𝑒 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑜𝑓 𝑜𝑏𝑗𝑒𝑐𝑡 𝑓𝑟𝑜𝑚 ℎ𝑜𝑙𝑒 = 𝑑 𝑖 𝑑 𝑜
ℎ 𝑖 ℎ 𝑜 = 𝑑 𝑖 𝑑 𝑜

35. Examples We will run through the examples on the board (pages 278-279)
Assignment
Page 280 # 1-7