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.

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.

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

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

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.

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

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

White Light is a mixture of many wavelengths or colors

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

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

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

Why is the shy blue?

Observation of interference effects with light. Fig. 16.12 Observation of interference effects with light. Fig. 16.12

Fig. 16.13 Fig. 16.13 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?

Fig. 16.18 Fig. 16.18 Interference can be seen from a single slit. Different points across the slit are sources of waves that can interfere at y.

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.

Fig. 16.14 Fig. 16.14 Interference can be seen when the layer thickness is around the wavelength of light.

Fig. 16.1 Fig. 16.1