1. 4.4 Wave Behaviors
Waves interact with media and each other in variety of ways.
Changes in speed or obstacles in their path will change their shape and direction.
Reflection
Refraction
Diffraction
Interference

2. Reflection - A wave meets a boundary, and is at least partially diverted backwards.

3. Reflection Law incident = reflect
The angles of the rays are always measured with respect to the normal which is perpendicular to the surface.
incident = reflect

4. Reflection Wave fronts.
Reflection and refraction
reflective surface
reflective surface
spherical
flat or straight
During reflection what happens to the frequency and the wavelength?

5. Reflected Rays come off hard boundary inverted and reversed in shape
Reflected Rays come off hard boundary inverted and reversed in shape. How does this show N3:?

6. Refraction
Refraction occurs when a wave meets a boundary, or a different medium , and is at least partially transmitted. The bending occurs because of a Dv.

7. Refraction of Wave-fronts Which side is faster? How can you tell?

8. Ex 1. Wavefronts strike the boundary between clear and muddy water and slow down. Sketch some new wavefronts entering the muddy water.
BOUN DARY
normal
INCIDENT WAVE
CLEAR WATER
MUDDY WATER

9. BOUN DARY REFRACTED WAVE incidence normal refraction
angle of incidence
REFRACTED WAVE
incidence
normal
refraction
angle of refraction
INCIDENT WAVE
CLEAR WATER
MUDDY WATER

10. Equations of Refraction
Index of refraction n = c/v. Ratio of speeds.
sin q1/sinq2 = constant = v1/v2
n1 sin q1 = n2 sinq2 (Snell’s Law)
Do This:
Show that n1/n2 = l2/l1.

11. 3. If a light wave enters glass (n = 1
3. If a light wave enters glass (n = 1.52) from air to make the refraction angle, qr = 35o:
Calculate
a. qi
b. the speed of light in glass.
c. Sketch the incident, refraction, and reflection ray, the qi , qr , and the reflection angle to scale. Sketch 4 wavefronts onto each ray.
a. 60o
b x 108 m/s

12. Snell’s Law
Problem Set

13. Do Now:
1. A ray of light enters air n=1.00 from water n = 1.33 at an incident angle of 59o. Calculate the angle of refraction. Sketch:
The incident ray,
Reflected ray,
Refracted ray.

14. Special Cases of Refraction
Critical angle
Dispersion

15. Critical Angle, qc. from slow to fast.
It is angle q1 that makes q2. 90o.
For air, n= 1 so:
n1 sin qc= 1 sin 90o .
sin qc= 1/ n1
. q1 beyond total internal reflection.

16. 2: The index of refraction of flint glass is 1. 47
2: The index of refraction of flint glass is What is the critical angle for light entering air from flint glass?

17. 3: The index of refraction of diamond is 2. 42
3: The index of refraction of diamond is What is the critical angle for light entering diamond from flint glass?

18. Dispersion

19. MP3

20. Diffraction = bending around boundary.

23. Size of obstacle

24. Video. Find the wave behaviors

25. Huygens’ Principle Models Wave Behavior
Every point on a wave-front is considered a source of secondary spherical wavelets which spread out in the forward direction at the speed allowed in the material.
The new wave-front is the tangential surface to all of the secondary wavelets.

26. Huygen’s Principle Predicts Refractive Angle for wavefronts.

27. Huygens wksht IB Questions

28. Huygens’ Principle Brian Lamore start from 58 sec

29. Light & EM waves

31. The Visible Spectrum
A range of light waves extending in wavelength from about 400 to 700 namometers.

32. Light & all EM waves are transverse, non-mechanical waves.

33. Electromagnetic Wave Velocity
The speed c is the same for all forms of EM waves in a vacuum of space.
It is ~ 3.0 x 108 m/s.
In air almost the same.
No mass can go the speed of light.
Nothing can go faster.

34. Amplitude is related to the wave energy. So is frequency
Amplitude is related to the wave energy. So is frequency. High Amplitude means bright. Higher f = higher energy change in color.

35. What is Light/EM waves
2 Models
1) Particles/Photons
Packets of energy
2) Electromagnetic Waves
energy-carrying waves emitted
by vibrating charges.
Light displays both types of behavior.

36. Mechanical Universe Optics

37. Every point on a wavefront serves as the source of spherical secondary wavelets, such that the wavefront becomes the envelope of these wavelets. The wavelets have the same frequency and speed as the original wavefront.