Download Watching TV, cordless phones, microwaves

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Chapter 15 Electromagnetic Radiation
As you read through the chapter answer the questions that follow. They are in order as
you read. You must answer in complete sentences, and so that I can read you’re writing
to receive credit. This is a quiz grade and is to be done individually.
Section 1 What are electromagnetic waves? Start reading on page 456.
1. How do we use electromagnetic (em) waves?
Watching TV, cordless phones, microwaves
2. How are waves produced? And what do they transmit?
Waves are produced by something that vibrates. They transmit energy
from 1 place to another
3. Why do sound and water waves need matter to transfer energy?
Sound and water waves need matter as energy is transferred from particle
to particle.
4. How do em waves differ from sound and water waves?
Electromagnetic waves do NOT require matter to transfer energy.
5. How do em waves travel?
Em waves travel by transferring energy between vibrating electric and
magnetic fields.
6. Magnets are surrounded by magnetic fields and electric charges are surrounded
by electric fields and both can exist in empty space.
7. Electrons are negatively charged subatomic particles. A). What generates
magnetic fields? B). What is an electric current? And C). What is this always
surrounded by?
A. The motion of electrons generates magnetic fields.
B. An electric current is the net flow of electrons in one direction.
C. Any moving electric charge is surrounded by a magnetic field as
well as an electric field.
8. Changing magnetic fields create changing electric fields which
produce currents.
9. Remember sound waves are produced when something vibrates. What vibrates
when em waves are produced?
An electric charge that moves back and forth produces an
electromagnetic wave.
10. Magnetic and electric fields continually create each other. They are perpendicular
or
at right angles to each other and travel outward from the moving charge. Why
is an em wave a transverse wave?
Em waves are transverse waves because they vibrate at right angles to the
direction the wave travels.
11. The energy transferred by em waves is called radiant energy.
12. Read and do Applying Math page 459, there are 4 numbers to rewrite.
A. 433 = 4.33 x 102
B. 812, 000, 000 = 8,12 x 108
C. 73, 000, 000, 000 = 7.3 x 1010
D. 84, 500 = 8.45 x 104
13. What is the speed of all em waves in a vacuum? What is the speed of light?
300, 000 Km/s
300, 000 Km/s
14. By what two ways can we describe electromagnetic waves? Define these terms.
A. Wavelength – The distance from one crest to another.
B. Frequency – The number of vibrations, or back and forth movements,
of the charge in one second. The frequency of an electromagnetic wave
equals the frequency of the vibrating charge that produces the wave.
15. How are frequency and wavelength related?
As frequency increases, wavelength decreases.
16. Electromagnetic waves can behave as waves and also as particles called
photons whose energy depends on the frequency of the waves. Sometimes particles
such as electrons can behave as waves.