Module 15

Question 1

Electromagnetic wave

Answer 1

Electromagnetic wave – A transverse wave composed of an oscillating electric field and a magnetic field that oscillates perpendicular to the electric field

Question 2

The Law of Reflection

Answer 2

The Law of Reflection – The angle of reflection equals the angle of incidence.

Question 3

Explain the wave theory of light

Answer 3

The wave theory of light views light as two transverse waves, one made of an oscillating magnetic field and the other an oscillating electric field.

Question 4

Explain the particle theory of light.

Answer 4

The particle theory of light views a ray of light as a beam of individual particles called photons.

Question 5

Explain the quantum-mechanical theory of light.

Answer 5

The quantum-mechanical theory says that light is both a particle and a wave. It is made up of individual packets that behave like particles, but the packet is actually made up of a wave.

Question 6

Sound waves cause air to oscillate. What do light waves oscillate?

Answer 6

Light waves oscillate a magnetic field and an electric field. Each one oscillates perpendicular to the other, as well as perpendicular to the direction of travel.

Question 7

What does Einstein’s Special Theory of Relativity say about the speed of light?

Answer 7

Einstein’s Special Theory of Relativity says that nothing with mass can travel faster than the speed of light.

Question 8

Light is traveling through water and suddenly breaks the surface and travels through air. Did light’s speed increase, decrease, or stay the same once it left the water?

Answer 8

Unlike sound, light travels slower in liquids than gases. Thus, the light’s speed increased once it left the water.

Question 9

Order the following colors in terms of increasing wavelength: orange, violet, yellow, green. In other words, list the color corresponding to the smallest wavelength first, and end with the color that corresponds to the longest wavelength.

Answer 9

The acronym ROY G. BIV allows us to remember the relative size of the colors’ wavelengths. Red is longest and violet is shortest. Thus, in terms of increasing wavelength, the colors are: violet, green, yellow, and orange.

Question 10

Order the following colors in terms of increasing frequency:

orange, violet, yellow, green.

Once again, start with the lowest frequency and end with the highest frequency.

Answer 10

Wavelength and frequency are inversely proportional. Thus, in terms of increasing frequency, it is the reverse of the previous order: orange, yellow, green, and violet.

Question 11

Do radio waves have higher or lower frequencies than visible light? What about X-rays?

Answer 11

Radio waves have wavelengths longer than visible light while X-rays have shorter wavelengths. This comes from Figure 15.3. Just like the visible light colors, you need not memorize any values for the wavelengths, but of the major categories in the figure, you need to know their relative wavelengths. Since frequency and wavelength are inversely proportional, radio waves have lower frequencies than visible light, while X-rays have higher frequencies.

Question 12

Infrared light is given off by any object that is losing heat. The human body is almost always losing heat to the environment. Why, then, don’t human bodies glow at night, since they are emitting light?

Answer 12

Infrared light is not visible. Thus, even though human bodies constantly emit infrared light, we cannot see that happening. There are special devices you can get that do, indeed, detect the infrared light that the human body emits. This allows you to see living organisms and other hot objects, even in the darkest of nights.

Question 13

Light hits a mirror, making an angle of 15 degrees relative to a line drawn perpendicular to the mirror’s surface. What angle does the reflected light make with the same line?

Answer 13

By the Law of Reflection, the reflected light also makes a 15 degree angle relative to that line.

Question 14

In the following diagram, will the man see his foot, despite the fact that the mirror does not reach the ground?

Answer 14

Yes. Remember, to see a part of his body, light must be able to travel from that part of his body, reflect off the mirror, and hit his eye. His brain will then extend that line backwards, forming an image in the mirror. The only constraint is that the light that strikes the mirror must obey the Law of Reflection:

Question 15

When light travels from one substance to another, what two things can happen to the direction of the light ray’s travel?

Answer 15

The light ray can be reflected or refracted.

Question 16

In a physics experiment, a light ray is examined as it travels from air into glass. If the angle that the light ray makes with a line perpendicular to the glass surface is measured, will the refracted ray bend toward or away from that line?

Answer 16

When light travels from a substance in which it moves quickly to a substance in which it moves slowly, the light bends towards the perpendicular. Since light moves faster in air than in glass, the light will bend towards the perpendicular line.

Question 17

When you look at objects underwater from above the water, they appear to be at a different position than their actual position. Why?

Answer 17

In order for you to see the objects underwater, light must travel from the object to your eyes. Thus, the light must travel out of the water and into the air. When light travels from water to air, it bends. This causes your mind to form a false image of the object in a slightly different location.

Question 18

In order for you to see a rainbow, what three conditions must be met?

Answer 18

There must be water droplets suspended in the air, the sun must be shining on them from behind you, and the sun must be at a certain angle (or height in the sky). The water droplets cause the refraction. In order to separate the colors enough to see them, however, the light must be refracted, reflected, and refracted again (see Figure 15.6). To do that, light must enter the water droplet on the side from which you are viewing it. Does not obey the Law of Reflection. The angle of reflection is clearly smaller than the angle of incidence. Thus, there is no way light can travel from his foot, reflect off the mirror, and hit his eye! 40 Solutions and Tests for Exploring Creation with Physical Science

Question 19

What is the difference between a converging lens and a diverging lens?

Answer 19

A converging lens causes light rays to bend so that they converge to a single point. Diverging lenses cause light rays to bend away from each other.

Question 20

Which of the following lenses is a converging lens? Which is a diverging lens?

Answer 20

The function of a lens depends on its shape. Lens (a) is a converging lens and lens (b) is a diverging lens.

Question 21

What is special about the way the eye focuses light as compared to the way a camera focuseslight?

Answer 21

The eye focuses light by changing the shape of its lens. A camera focuses light by moving the position of the lens. The eye’s method is faster and much more precise.

Question 22

Suppose the cone cells on your retina that sense red light no longer work. If you look at a whitepiece of paper, what color would it appear to be?

Answer 22

If your red cone cells no longer worked, your brain would think that you never saw red light. When the white light reflected off of the paper and hit your eyes, then, your green cone cells would send signals to your brain, as would your blue cone cells. As a result, the white paper would appear to be blue-green or cyan.

Question 23

Suppose the cone cells on your retina that sense red light no longer work. If you look at a red piece of paper, what color would it appear to be?

Answer 23

If your red cone cells no longer worked, your brain would think that you never saw red light. If you looked at a red piece of paper, it is red because it only reflects red light. Thus, it would send only red light to your eyes. You cannot see red light, however, so the red paper would appear to be black. In actual fact, it would probably appear gray, because the other cells in your eyes (rods) detect the presence of light without detecting color. Thus, your brain would receive signals from the rods telling it that light was there, but there would be no cone cell signals to indicate the color. The brain would be a bit confused, but it would probably form a grayish image, as if you were seeing only in black and white.

Question 24

A shirt is dyed so that it looks violet. What colors of light does the dye absorb?

Answer 24

In order to look violet, it must absorb all colors except violet. Thus, it absorbs red, yellow, orange, green, blue, and indigo light.

Question 25

A cyan dye is made of a mixture of substances that absorb all light colors except blue and green. If you took a cyan piece of paper and placed it in a dark room and shined red light on it, what would you see?

Answer 25

Since cyan absorbs all colors except blue and green, it will absorb any red light shone on it. As a result, no light will make it to your eyes. In red light, then, the paper would look black.

Question 26

A cyan dye is made of a mixture of substances that absorb all light colors except blue and green. If you took a cyan piece of paper and placed it in a dark room and shined green light on it, what would you see?

Answer 26

Since cyan absorbs all colors except blue and green, When you shined green light on it, the green light would be reflected. There would be no blue to mix with it, though. In green light, the paper would look green.