1. Reading Quiz
Sometimes a thin layer of oil on top of a puddle of water produces a rainbow pattern of colors. This is a result of:
the interference properties of waves.
the oil having the shape of a prism.
the transverse nature of electromagnetic waves.

2. Quiz Question 1:
Compare sound waves with electromagnetic waves. Which of these statements is FALSE?
A. Electromagnetic waves travel faster than sound waves.
B. For both types, the wave velocity equals the wave length times the frequency (v=lf).
C. Both sound and electromagnetic waves are transverse waves.
D. Electromagnetic waves can travel through vacuum, but sound waves cannot.

3. This demonstration showed how a changing magnetic field produced a changing electric field; further, a changing electric field produces a changing magnetic field.

4. Fig. 16.2
A changing current in an antenna causes changing electric and magnetic fields.
Fig. 16.2

5. Speed of light c = 2.98 x 108 meters/sec
Fig. 16.3
Speed of light c = 2.98 x 108 meters/sec
Example: Plane Wave
Fig. 16.3
Light is an electromagnetic wave with changing electric and magnetic fields.

6. A method for measuring the speed of light.
Fig. 16.4
Fig. 16.4
A method for measuring the speed of light.

7. Speed c = lf Visible Light: 380nm to 750nm nm=nanometers or10-9 m
Fig. 16.5
Speed c = lf
Fig. 16.5
Visible Light: 380nm to 750nm
nm=nanometers or10-9 m

8. White Light is a mixture of many wavelengths or colors

9. Retina is made of rods and cones
Cones give color vision, concentrated in the center called the fovea
Rods are distributed throughout the retina, night and peripheral vision.
(no color vision0

10. There are three types of color sensitive cones in the eye.
Additive Color mixing

11. Selective absorption is a subtractive process.
Cyan, yellow, magenta
The surface absorbs light of a given color
Mirror like
All directions
The light can be reflected
In one of two ways

12. Why is the shy blue?

13. Observation of interference effects with light.
Fig
Observation of interference effects with light.
Fig

14. Fig
Fig
What happens if the path difference at the point y is half a wavelength?
What happens if the path difference at y is a full wavelength? Or 2l? Or 3l?

15. Fig
Fig
Interference can be seen from a single slit. Different points across the slit are sources of waves that can interfere at y.

16. Question 2:
In a double slit interference experiment, what happens when the distance d between slits gets smaller?
The spots on the wall move closer together.
The spots move farther apart.
The spots don’t move, but become dimmer.
The spots don’t move, but become brighter.

17. Fig
Fig
Interference can be seen when the layer thickness is around the wavelength of light.

18. Fig. 16.1
Fig. 16.1