Unit 6
Fireflies are an example of which of the following processes dealing with light?
Bioluminescence
A red object viewed through a blue filter would appear to be _____.
Black
What color does yellow pigment subtract from white light?
Blue
What do you see when red light shines on a cyan pigment?
Blue
What is the order of the electromagnetic spectrum from highest to lowest energy?
Gamma Rays, X-Rays, Ultraviolet Rays, Visible Light, Infrared Waves, Microwaves, Radio Waves
What is the difference between the prefixes "infra" and "ultra"?
Infra means below; ultra means above.
In order to keep its food hot, a restaurant will place it under which type of lamp?
Infrared
Which one of the following types of EM radiation is associated with warming or heat sensitive?
Infrared
Which type of radiation is used to detect lava flows or oil deposits?
Infrared
What is the placement of infrared and ultraviolet radiation with respect to visible light radiation on the electromagnetic spectrum?
Infrared radiation has a frequency below visible; ultraviolet radiation has a frequency above visible.
The phenomenon of _____ is described when excited electrons don't fall back to the ground state immediately.
Phosforescence
What is the main difference between sound and electromagnetic waves?
Sound are mechanical waves; electromagnetic waves are non-mechanical waves.
If you know the wavelength of any form of electromagnetic radiation, you can determine its frequency because
all wavelengths travel at the same speed.
When the waves are out of phase, their amplitudes _____ for ______ interference.
cancel out; destructive
Define frequency
A property of a wave that describes how many wave patterns or cycles pass by in a period of time. Frequency is often measured in Hertz (Hz), where a wave with a frequency of 1 Hz will pass by at 1 cycle per second.
Who discovered that a changing electric field could produce a magnetic field?
Clerk Maxwell
A pigment always absorbs its _____.
Complement
Define infrared light
Electromagnetic radiation at wavelengths longer than the red end of visible light and shorter than microwaves (roughly between 1 and 100 microns). Almost none of the infrared portion of the electromagnetic spectrum can reach the surface of the Earth, although some portions can be observed by high-altitude aircraft (such as the Kuiper Observatory) or telescopes on high mountaintops (such as the peak of Mauna Kea in Hawaii).
Define ultraviolet light
Electromagnetic radiation at wavelengths shorter than the violet end of visible light; the atmosphere of the Earth effectively blocks the transmission of most ultraviolet light.
Which is the correct statement regarding the use of electromagnetic radiation in the treatment of cancer?
High frequency gamma rays are used because they kill cancer cells before healthy cells.
"Light produced by heating atoms" describes which of the following terms?
Incandescence
Maxwell calculated what the speed of light would have to be in order to obey which law?
Law of Conservation of Energy
Who discovered that a changing magnetic field produced an electric field?
Michael Faraday
Which of the following types of waves are used in satellite communciations?
Microwaves
Which portion of the electromagnetic spectrum is used in aircraft navigation?
Microwaves
Which type of EM wave causes food molecules to vibrate sympathetically?
Microwaves
Which portion of the electromagnetic spectrum is used in a television?
Radio Waves
The color of an opaque object depends on the color of light it _____.
Reflects
The concept of resonance explains ....
The collapse of the Tacoma Narrows Bridge, the reception of radio waves by antennae, and the cooking of food by microwaves.
Define wavelength
The distance between adjacent peaks in a series of periodic waves.
Define gamma rays
The highest energy, shortest wavelength electromagnetic radiations. Usually, they are thought of as any photons having energies greater than about 100 keV.
Why does your arm feel warm when sunlight comes through glass?
The infrared radiation can penetrate the glass; the UV cannot.
Which of the following is not a luminous object?
The moon
True or False: Radio waves cannot be heard.
True
Which is the lowest frequency end of the ultraviolet range of the electromagnetic spectrum?
UVA
Which portion of the electromagnetic spectrum is used to sterilize medical instruments?
Ultraviolet Light
What is necessary to produce any electromagnetic radiation?
Vibrating Charge
Place all the other colors in order based on their wavelength from shortest to longest.
Violet
To which one of the following types of EM radiation is the human eye sensitive?
Visible Light
What color clothing is best to wear in the desert during the day?
White
AM stands for
amplitude modulated
That light can undergo interference is evidence that it:
behaves like a wave.
What is the symbol for the speed of light?
c
FM stands for
frequency modulated
Radio waves ....
have the longest wavelength on the EM spectrum
What type of radiation is used in a heat lamp in a fast food restaurant to keep the french fries warm?
infrared
LASER is an acronym for
light amplification by stimulated emission of radiation
What are the primary subtractive colors?
magenta, cyan, yellow
Which one of the following is described as "light producing electricity"?
photoelectric
vhf and uhf are part of which section on the electromagnetic spectrum?
radio
TV and radar are included in which type of electromagnetic radiation?
radio waves
The primary light colors are ___.
red, blue, green
All electromagnetic waves have the same _____.
speed in space
In a vacuum, electromagnetic radiation of short wavelengths ...
travels as fast as radiation of long wavelengths.
The particles that produce electromagnetic waves must be ____ and ____.
vibrating; charged
Find the frequency of x-rays of wavelength 10^-10 m. (c = 3 x 10^8 m/s)
3 x 10^18 Hz
What is the value of the speed of light?
3 x 10^8 m/s
What is the relationship between the frequency of an electromagnetic wave and the energy it radiates?
As the frequency increases, the energy increases.
Define visible light
Electromagnetic radiation at wavelengths which the human eye can see. We perceive this radiation as colors ranging from red (longer wavelengths; ~ 700 nanometers) to violet (shorter wavelengths; ~400 nanometers.)
Define x-rays
Electromagnetic radiation of very short wavelength and very high-energy; X-rays have shorter wavelengths than ultraviolet light but longer wavelengths than gamma rays.
Define microwaves
Electromagnetic radiation which has a longer wavelength (between 1 mm and 30 cm) than visible light. Microwaves can be used to study the Universe, communicate with satellites in Earth orbit, and cook popcorn.
Define radiation
Energy emitted in the form of waves or particles
True or False: UV rays can penetrate glass and give you a sunburn.
False
Why do microwaves cook from the inside out?
Fats, proteins and carbohydrates inside the food have frequencies that match those of the microwaves, so they vibrate and generate heat which cooks the food.
Which of the following terms is described by UV light exciting electrons that make large leaps and then fall in smaller steps?
Fluroescence
The energy of electromagnetic radiation depends on its _____.
Frequency
Of the various types of electromagnetic radiation, which is the most penetrating through all forms of matter?
Gamma
Which type of radiation has the highest frequency on the electromagnetic spectrum?
Gamma
Who discovered X-rays?
Wilhelm Roentgen
When red light and green light shine on the same place on a piece of white paper, the spot appears to be
Yellow
When red light and green light shine on the same place on a piece of white paper, the spot appears to be ...
Yellow
Which of the following is NOT an additive primary (light) color?
Yellow (blue, red, green)
Define electromagnetic spectrum
the range of all types of EM radiation
For visible light (ROYGBIV), which has the shortest wavelength? Which has the longest?
violet, indigo, blue, green, yellow, orange, red
The first laser ...
was based on one of Einstein's ideas
Interference effects observed in the early 1800's were instrumental in supporting a concept of the existence of which property of light?
wave nature
