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Electromagnetic Radiation Fundamentals
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Electromagnetic Radiation Fundamentals
Electromagnetic Radiation Fundamentals
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1
Question
What dual nature characterizes electromagnetic radiation according to the classical wave model and photon packet description?
Page 103
Answer
Electromagnetic radiation exists both as Maxwell’s waves and as streams of discrete particles called photons.
2
Question
How are photons exchanged in electromagnetic radiation interactions?
Page 103
Answer
Photons are exchanged whenever electrically charged subatomic particles interact.
3
Question
What are the manifestations of electromagnetic radiation listed from high to low energy regions?
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Answer
Manifestations include X-rays, gamma rays, ultraviolet light, visible light, microwaves, and radio frequency radiation.
4
Question
How do energies change across the electromagnetic spectrum regions?
Page 103
Answer
Energies change dramatically from radio waves to gamma radiation.
5
Question
What classical model describes properties of electromagnetic radiation including wavelength frequency velocity and amplitude?
Page 103
Answer
Sinusoidal wave model describes wavelength, frequency, velocity, and amplitude.
6
Question
Does electromagnetic radiation require a supporting medium for transmission?
Page 103
Answer
Electromagnetic radiation requires no supporting medium and passes readily through a vacuum.
7
Question
Why does the sine wave model fail to fully describe absorption and emission of radiant energy?
Page 103
Answer
The sine wave model does not provide the total picture for absorption and emission processes.
8
Question
What particle description complements the wave model for electromagnetic radiation absorption and emission?
Page 103
Answer
EMR exists as a stream of discrete particles or packets of energy called photons.
9
Question
What determines the energy of a photon in electromagnetic radiation?
Page 103
Answer
Photon energy depends on the frequency of the radiation.
10
Question
How are electric and magnetic fields oriented in a monochromatic beam of plane-polarized light?
Page 103
Answer
Electric and magnetic fields undergo in-phase sinusoidal oscillation at right angles to each other and to the direction of propagation.
11
Question
What does the amplitude of an electromagnetic sine wave represent?
Page 103
Answer
Amplitude is the length of the electric vector at maximum peak height.
12
Question
How is the period defined for an electromagnetic waveform?
Page 103
Answer
Period is the time in seconds required for the passage of successive maxima or minima through a fixed point in space.
13
Question
What is the unit for frequency of electromagnetic radiation oscillations?
Page 103
Answer
Frequency unit is hertz (Hz), corresponding to one cycle per second.
14
Question
How is frequency mathematically related to the period of a waveform?
Page 103
Answer
Frequency equals 1 divided by the period.
15
Question
What does wavelength measure in successive electromagnetic waveforms?
Page 103
Answer
Wavelength is the linear distance between any two equivalent points on successive waveforms.
16
Question
What are common units for wavelength in the visible spectrum of electromagnetic radiation?
Page 103
Answer
Widely used unit is nanometer (nm = 10^-9 m).
17
Question
What unit expresses wavelength for X-ray or gamma regions of electromagnetic radiation?
Page 103
Answer
Angstrom units (Å = 10^-10 m).
18
Question
What unit is used for longer wavelengths in the infrared region of electromagnetic radiation?
Page 103
Answer
Micrometer (μm = 10^-6 m).
19
Question
What equation determines velocity of propagation for electromagnetic radiation?
Page 103
Answer
Velocity v_i equals frequency times wavelength: v_i = n l_i (Equation 4-1).
20
Question
What remains constant for light frequency determined by its source in different media?
Page 103
Answer
Frequency of light is determined by the source and does not change.
21
Question
How does the propagation medium affect wavelength of electromagnetic radiation?
Page 103
Answer
Velocity depends on the composition of the medium, so wavelength varies accordingly.
22
Question
What is the maximum velocity of light traveling through a vacuum?
Page 103
Answer
Velocity c is 2.99792 × 10^8 m/s, rounded to 3.00 × 10^8 m/s.
23
Question
What equation relates vacuum light speed frequency and wavelength?
Page 103
Answer
c = v l_i (Equation 4-2).
24
Question
Why is propagation of radiation slowed in any medium containing matter?
Page 103
Answer
Interaction between EMR field and electrons bound in atoms of matter slows propagation.
25
Question
How does radiant frequency behave as radiation passes from air to a thicker medium like water?
Page 103
Answer
Radiant frequency does not vary and remains fixed by the source.
26
Question
What happens to wavelength as radiation passes from air to a thicker medium if frequency is fixed?
Page 103
Answer
Wavelength must decrease as radiation passes from air to a thicker medium.
27
Question
What equation expresses the energy of a photon in terms of frequency or wavelength?
Page 103
Answer
E = h v = h c / l (Equation 4-3).
28
Question
What is the value of Planck’s constant in the photon energy equation?
Page 103
Answer
h = 6.626 × 10^-34 J s.
29
Question
In what units is photon energy often stated besides joules?
Page 103
Answer
Electron volts (eV).
30
Question
What conversion factors relate joules to electron volts for photon energy?
Page 103
Answer
1 J = 6.24 × 10^18 eV; 1 eV = 1.602 × 10^-19 J.