Chapter 29 HW

What accounts for the different colors in a soap bubble?

Light reflecting from the outer and inner surfaces of the bubble travels different distances.

For an opening of a given size, is diffraction more pronounced for a longer wavelength or for a shorter wavelength?

Longer wavelengths

What phenomenon distinguishes longitudinal waves from transverse waves?

Polarization

How much ordinary light will an ideal Polaroid transmit?

50%

A hologram is the result of light _________.

interference

Which more easily diffracts around buildings, AM or FM radio waves? Why?

AM waves, because the wavelengths are a hundred times longer than FM waves

PART A Select the Light tab, with no barrier. Select a wavelength so that the light is red, and adjust the amplitude of the light to the highest setting. Light is a form of electromagnetic wave, containing oscillating electric and magnetic fields. Select Add Detector, which shows how the electric field oscillates in time at the location of the probe. The amplitude of the wave at the location of the probe is equal to the maximum electric field measured. How does the amplitude of the wave depend on the distance from the source? PART B Select Show Screen to place a screen on the right edge of the panel. You might also want to select the Plot Intensity graph to see the details more clearly. Which statement best describes how the intensity of the wave depends on position along the screen? PART C Now, select a barrier with one slit, and use the Barrier Location slider bar to place it roughly 1295 nm away from the light source (second tick mark on the slider bar). Adjust the slit width (using the slider bar) to roughly 262 nm (first tick mark). Keep the wavelength of the light set to red. Which statement best describes how the intensity of the wave depends on position along the screen? PART D Now, select Two Slits and a slit separation of roughly 1750 nm. (Keep the slit widths and barrier location the same as in Part C, and be sure the amplitude is still set to the highest setting). Which statement best describes how the intensity of light on the screen behaves? PART E In the previous part, you learned about the interference pattern that produces several fringes on the screen. To make the fringes more visible, adjust the wavelength of the light to make the light green. You should see a fringe in the middle of the screen, and several others above and below the middle. Click on Show Graph (near the bottom of the window), and then press the blue pause button (at middle-bottom of the screen). Use the measuring tape to measure the wavelength of the green light (you can measure from crest to crest in the Electric field vs. Position plot). Make a note of this wavelength measurement to use as a reference when we compare two other distances next. Now, measure the distance from the first bright fringe above the middle of the screen to the upper slit. Call this distance r1. Next, measure the corresponding distance to the lower slit, r2. The distances r1 and r2 are shown in the figure for clarity PART F Compare the distances from the first location nearest the middle of the screen where the intensity is nearly zero (dark fringe) to each of the two slits. How do the distances compare? PART G How does the distance between consecutive bright fringes depend on the wavelength of the light? PART H How does the distance between consecutive bright fringes depend on the slit separation? PART I How does the distance between the bright fringes depend on the slit width (for slit widths less than the wavelength of the light)? PART J How does the distance between the bright fringes depend on the amplitude of the wave? PART K Does interference occur when water or sound waves encounter a barrier with two slits?

A-The amplitude decreases with distance. B-The intensity is roughly constant. C-The intensity is roughly constant. D-The intensity is large near the middle of the screen, then decreases to nearly zero, and then increases again as the distance from the middle of the screen increases. E-The difference in the distances is equal to the wavelength of the wave. F-The difference in the distances is equal to half the wavelength of the wave. G-The fringes get farther apart as wavelength increases. H-The fringes get closer together as the slit separation increases. I-The spacing of the fringes does not change when the slit width changes. J-The spacing of the fringes does not change when the amplitude changes (just the brightness changes). K-Yes, interference also occurs for both of these types of waves.

PART A When light bounces off a surface, which component will be reflected more - the component that is parallel to the surface, or the component that is perpendicular to the surface, and why PART B When light with both horizontal and vertical components is incident on a vertical side of a stone cliff, which component of light is more strongly reflected? PART C If you were a rock climber, would you want to wear the same glasses to prevent glare as you did when you were driving, and why PART D What kind of glasses would you wear while watching 3D movies, and why?

A-We can expect the component that is parallel to the surface to reflect more, because it aligns with the surface - similar to a flat rock bouncing off the surface of water. B-vertical component C-No. While you were driving, the polarization angle of your glasses was aligned vertically to block horizontal glare from the road. For the glasses to block vertical glare from the rock face, the polarization angle would have to be aligned horizontally. D-glasses with one horizontally polarized and one vertically polarized lens, because one projector is horizontally polarized and the other is vertically polarized

Is interference restricted to only some types of waves or does it occur for all types of waves?

All types of waves

Why are interference colors primarily cyan, magenta, and yellow?

Interference acts mainly to cancel the reflection of one color, and removing one color at a time from white light produces cyan, magenta, and yellow.

What is the cause of Newton's rings?

Interference between light reflected from the top and bottom of an air gap when the curvature side of a convex lens rests on a flat glass

What role do polarization filters play in three-dimensional projection?

Polarizing filters allow the left-eye image to be seen only by the left eye, and the right-eye image to be seen only by the right eye.

How does a hologram differ from a conventional photograph?

The hologram appears to be three dimensional. You can look around objects in a hologram.

Will light pass through a pair of Polaroids when the axes are aligned? When the axes are at right angles to each other? Why?

The light that passes through the first Polaroid comes out completely polarized in the direction of that polarizer, so it easily passes through the analyzer with an aligned axis but not through one with an axis at right angles.

What aspect of light did Thomas Young demonstrate in his now-famous light experiment?

The principle of superposition known as interference

Will plane waves incident upon a small opening in a barrier fan out on the other side or continue as plane waves?

They will fan out and decrease in amplitude.