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