# Apologia Physical Science Module #15 Study Guide

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

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

Explain the wave theory of light, the particle theory of light, and the quantum-mechanical theory of light.
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. The particle theory of light views a ray of light as a beam of individual particles called photons. 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.

Sound waves cause air to oscillate. What do light waves oscillate?
Light waves oscillate a magnetic field and an electric field.

What does Einstein’s special theory of relativity say about the speed of light?
It says that nothing with mass can travel faster than the speed of light.

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

Order the following colors in terms of increasing wavelengths: 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.
Violet, green, yellow, orange.

Order the colors in question six (colors: orange, yellow, green and violet) in terms of increasing frequency. Once again, start with the lowest frequency and end with the highest frequency.
Orange, yellow, green, violet.

Do radio waves have higher or lower frequencies than visible light? What about x-rays?
Radio waves have lower frequencies then visible light, while x-rays have higher frequencies.

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?
Infrared light is not visible.

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?
The reflected light also makes a 15 degree angle relative to that line.

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

When light travels from one substance to another, what two things can happen to the direction of the light ray’s travel?
The light ray can be reflected or refracted.

In a physics experiment, a light Ray is examined as it travels from air into the 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?
The light will bend towards the perpendicular line.

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

In order for you to see you a rainbow, what three conditions must be met?
There must be water droplets suspended in the air, the sun must be shining on them from behind you, in the sun must be at a certain angle (or height in the sky).

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

which of the following lenses is a converging lens? Which is a diverging lens?
Lens (a) is a converging lens and lens (b) is a diverging lens.

What is special about the way the eye focuses light as compared to the way a camera focuses light?
The eye focuses light by changing the shape of its lens. A Camera focuses light by moving the position of the lens.

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

A shirt is dyed so that it looks violet. What colors of light does the dye absorb?
Red, blue, orange, yellow, and indigo light.

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? What would you see if you shined green light on it?
In red light, the paper would look black. In green light, the paper would look green.