Science module 15
Electromagnetic wave:
A transverse wave composed of an oscillating electric field and a magnetic field that oscillates perpendicular to the electric field.
Speed of light
Is a fundamental physical constant that is the speed at which electromagnetic radiation travels in a vacuum and that has a value of 299,792,458 meters per second.
Diverging lens
A type that causes parallel rays of light to spread out or diverge.
15.2 Suppose a photon is traveling through air. If the particle suddenly hits a lake, what will happen to it's speed?
According to Table 15.1 light has a speed of 220,000,000 m/sec in fresh water. Thus, when the photon hits the lake, it must slow down.
15.7 A man is spear fishing. He looks into the water and sees a fish in front of him. When he aims his spear, should he aim it at the fish, in front of the fish, or behind the fish
The man must aim in front of the fish he sees.
The law of reflection
The angel of reflection equals the angel of incidence.
Frequency/wavelength of light
The number of oscillations completed in one second is called the frequency of a wave.
Human eye (Label parts)
Cornea, aqueous humor, lens, Vitreous humor, retina, optic nerve.
15.3 Without looking at figure 15.2 or figure 15.3, order the following colors in terms of increasing frequency: Yellow, indigo, red, green.
You can remember the relative of light with the acronym ROY G. BIV. Red has the longest wavelength, and violet has the shortest. With that knowledge then, we can say that for the colors given, red has the longest wavelength, yellow is next, followed by green. Indigo has the shortest wavelength. However, the question asked about frequency. The longer the wavelength, the lower the frequency. Thus, in terms of increasing frequency it is red, yellow, green, indigo.
15.8 consider the two lenses pictured below. Which one focuses light rays closest to the lens?
think about it: Lenses work because of their curvature. The more curvature they have, the more they will do their job. Thus, lens (b) will focus the light rays closest.
Particle theory
A scientific model that explains the characteristic and behavior of matter.
Electromagnetic spectrum
The range of all types of EM radiation
Additive primary colors
Additive primary are colors white added together.
15.4 If radio signals are really made up of electromagnetic waves, why doesn't a radio station's antenna glow when it transmits its signals?
A radio station's antenna does not glow because the light it emits is not visible. Radio waves have wavelengths longer than visible light.
15.9 Suppose you have two flashlights. You cover the first with green cellophane and shine it on a mirror. When you look at the mirror, you see a green spot of light. If you were to then take the second flashlight, cover it with red cellophane, and shine it on the same part of the mirror on which the green spot is still shinning what color would you see?
The mirror reflects all wavelengths that hit it. When the green hits it, it will reflect green. When the red hits it, it reflects red. When both hit it, it will reflect both. When your eyes see both colors, your brain will add them to make yellow.
Wave theory
Light is transmitted from luminous bodies to the eye and other objects by undulatory movement.
Reflection
Reflection occurs when light traveling through one material bounces off a different material.
Subtractive primary colors
The three colors in the visible light spectrum that are produced when either red, green, or blue light is absorbed or subtracted and the unabsorbed colors are reflected or transmitted.
15.5 Draw the path of the light ray in the diagram below to show where the light eventually hits the screen
Each time the light is reflected, the angle it makes with the perpendicular must be the same before and after reflection.
15.10 Suppose you took a red shirt and put it in a dark room. Then, suppose you took a flashlight and covered it with green cellophane as described above. If you were to go into a dark room and shine the green cellophane covered flashlight on the red shirt, what color would you see? Assume the dye on the shirt uses the subtractive primary colors to make its light.
The red shirt is red because when light light strikes it, it absorbed all wavelengths except red. It does this by mixing yellow and magenta. The yellow absorbs all wavelengths except red and green, and the magenta absorbs all wavelengths except red and blue. Thus, Red is the only wavelength reflected from the shirt. When the green light shines on it, the green light will be absorbed by the magenta. Nothing will be reflected back. Thus, The shirt will look black. In fact it won't even look like a shirt. Without any light reflecting back from it, you will not even see the shirt.
Quantum-mechanical theory of light
Describes that matter and light consists of minute particles that have properties of waves that are associated with them.
Refraction of Light
The change in direction of a wave passing from one medium to another.
15.1 Which of the pictures below is the best illustrations of the quantum-mechanical theory of light?
Remember, in the quantum-mechanical view (the currently accepted theory on the nature of light) light is made up of little packets of waves. Thus (b) is the best illustration of the current view of light. The picture in (a) would be true if light were a pure wave, and the picture in (c) would be true if light were made up of a stream of pure particles.
15.6 the following is a diagram of how a light ray travels from substance A through substance B: Does light travel more quickly in substance A or substance B?
The refracted light ray bends away from the perpendicular when traveling from substance A to substance B. When light travels into a substance in which it moves more quickly, the light bends away from the perpendicular. Thus, light travels more quickly in substance B than in substance A.
Did you enjoy this game yes or no
Yes