1. Waves

2. Objectives State the law of reflection.
Compare and contrast refraction and diffraction.
Identify wave interference.
CLE Investigate the properties and behaviors of mechanical and electromagnetic waves.

3. The Behavior of Waves
Reflection occurs when a wave strikes an object and bounces off of it

4. - the bouncing back of a wave. 1) Sound echoes
Reflection
- the bouncing back of a wave.
1) Sound echoes
2) Light images in mirrors
3) Law of reflection
i = r

5. All types of waves can be reflected
The angle of incidence of a wave is always equal to the angle of reflection

6. The Behavior of Waves
Normal – an imaginary line perpendicular to a reflective surface
Angle of incidence – the angle formed by the wave striking the surface and the normal

7. Angle of reflection – the angle formed by the reflected wave and the normal

8. A. Reflection Reflection when a wave strikes an object and bounces off
Normal
Reflection
when a wave strikes an object and bounces off
incident beam
reflected beam

9. Incidence – Reflection w/Normal

10. The Behavior of Waves
Refraction – the bending of a wave caused by a change in its speed as it moves from one medium to another

12. The Behavior of Waves
The greater the change in speed is, the more the wave bends
When a wave passes into a material that slows it down, the wave is bent toward the normal
When a wave passes into a material that speeds it up, the wave is bent away from the normal

13. Refraction of Light in Water
Light waves travel slower in water than in air. This causes light waves to change direction when they move from water to air or air to water.
When light waves travel from air to water, they slow down and bend toward the normal.

15. Prism refracts the light twice -once when it enters the prism and
again when it leaves the prism.

16. B. Refraction
Example:
View explanation.

17. Diffraction
Diffraction - the bending of a wave around the edge of an object.

18. 1) Water waves bending around islands
2) Water waves passing through a slit and spreading out

19. 3. Diffraction depends on the size of the obstacle or opening compared to the wavelength of the wave.
Less occurs if wavelength is smaller than the object.
More occurs if wavelength is larger than the object.

20. 4) AM radio waves are longer and can diffract around large buildings and mountains; FM can’t.

21. Wave Interference
Interference – the ability of two or more waves to combine and form a new wave

22. The Behavior of Waves
Waves pass right through each other and continue in their original direction
New wave exists only while the two original waves continue to overlap

23. The Behavior of Waves
Constructive interference – waves add together

24. The Behavior of Waves
Destructive interference – waves subtract from each other

25. D. Interference Interference constructive  brighter light
destructive  dimmer light

26. The Behavior of Waves
Standing waves – a wave pattern that stays in one place
Form when waves of equal wavelength and amplitude that are traveling in opposite directions continuously interfere with each other

27. Nodes – the places where two waves always cancel each other
Standing wave
Nodes – the places where two waves always cancel each other
node
antinode

28. Nodes

29. Resonance – the ability of an object to vibrate by absorbing energy at its natural frequency

30. How do you think wave behaviors apply to music?
Constructive interference causes sound waves to become louder; destructive interference causes sound waves to become more quiet. Standing waves create rich, even, constant tones in music.

31. What is the difference between refraction and reflection?
Section Check 2
Question 2
What is the difference between refraction and reflection?
Answer
Refraction occurs if a light wave changes speed in moving from one material to another. Reflection occurs when light waves are returned or thrown back from a surface.

32. Sonic Boom vs Boom Cone