Physics Ch. 24
Which one of the following wavelengths is in the infrared range of the electromagnetic spectrum?
20 µm
The electric field E of an electromagnetic wave traveling the positive x direction is illustrated in the figure. This is the wave of the radiation field of an antenna. What are the direction and the phase relative to the electric field of the magnetic field at a point where the electric field is in the negative y direction?
-z direction, in phase
A linearly polarized electromagnetic wave is sent through two sheets of polarizing material. The first sheet, A, is oriented so that its transmission axis makes an angle of 30∞ with respect to the incident electric field of the wave. The second sheet, B, is oriented so that its transmission axis makes an angle of 90∞ with the incident electric field of the wave. The incident beam has an electric field of peak magnitude E0 and average intensity S0. What is the average intensity of the wave after it passes through B?
0.19S0
A linearly polarized electromagnetic wave is sent through two sheets of polarizing material. The first sheet, A, is oriented so that its transmission axis makes an angle of 30∞ with respect to the incident electric field of the wave. The second sheet, B, is oriented so that its transmission axis makes an angle of 90∞ with the incident electric field of the wave. The incident beam has an electric field of peak magnitude E0 and average intensity S0. What is the average intensity of the wave after it passes through A?
0.75S0
A linearly polarized electromagnetic wave is sent through two sheets of polarizing material. The first sheet, A, is oriented so that its transmission axis makes an angle of 30∞ with respect to the incident electric field of the wave. The second sheet, B, is oriented so that its transmission axis makes an angle of 90∞ with the incident electric field of the wave. The incident beam has an electric field of peak magnitude E0 and average intensity S0. What is the peak value of the electric field amplitude after it goes through sheet A?
0.87E0
Note the different types of electromagnetic radiation: (1) X-rays (4) visible light (2) radio waves (5) infrared radiation (3) gamma rays (6) ultraviolet radiation Which list correctly ranks the electromagnetic waves in order of increasing frequency?
2, 5, 4, 6, 1, 3
Linearly polarized light is incident upon a polarizing sheet that has a transmission axis is parallel to the incident light. The sheet is rotated about its axis through 360∞ (one complete revolution). At how many positions, including the initial and final positions, will the transmitted intensity be a maximum?
3
Two polarizing sheets have their transmission axes parallel so that the intensity of unpolarized light transmitted through both of them is a maximum. Through what angle must either sheet be rotated if the transmitted intensity is 25 % of the incident intensity?
45 degrees
What would the speed of an observer be if a red (4.688 ◊ 1014 Hz) traffic light appeared green (5.555 ◊ 1014 Hz) to the observer?
5.548 ◊ 107 m/s
An astronomer observes electromagnetic waves emitted by oxygen atoms in a distant galaxy that have a frequency of 5.710 ◊ 1014 Hz. In the laboratory on earth, oxygen atoms emit waves that have a frequency of 5.841 ◊ 1014 Hz. Determine the relative velocity of the galaxy with respect to the astronomer on the earth. Note: The speed of light is 2.9979 ◊ 108 m/s.
6.724 * 106 m/s, away from earth
A minivan moving at 38 m/s passes an unmarked state police car moving at 24 m/s. The electromagnetic waves produced by the radar gun in the police car have a frequency of 8.25 ◊ 109 Hz. What is the magnitude of the difference in frequency between the waves emitted by the gun and those that are reflected back from the speeding minivan?
770 Hz
Which one of the following will not generate electromagnetic waves or pulses?
A steady direct current
Which one of the following statements concerning electromagnetic waves is false?
Electromagnetic waves are longitudinal waves.
. Light emerges from a polarizer that has its transmission axis located along the x axis. The light then passes through two additional sheets of polarizing material. It is desired to orient the two sheets so that, after passing through both of them, the electromagnetic wave has the maximum possible intensity and is polarized 90∞ with respect to the x axis. How should the transmission axes of the sheets be oriented? Note: the following answers give the angles that the transmission axes make with respect to the x axis.
First polarizing sheet: 45 degrees with respect to the x axis Second polarizing sheet: 90 degrees w/respect to the x axis
The electromagnetic wave of the radiation field from a wire antenna travels toward the plane of your paper (which is in the -z direction). At time t = 0 s, the wave strikes your paper at normal incidence. The magnetic field vector at point O in the figure points in the -y direction and has a magnitude of 4.0 ◊ 10^-8 T. The frequency of the wave is 1.0 ◊ 10^16 Hz. What is the direction of the electric field?
It points in the positive x direction.
Which one of the following scientists did not attempt to measure the speed of light?
Maxwell
Which one of the following statements concerning electromagnetic waves is false?
X-rays have longer wavelengths than radio waves.
Which one of the following statements concerning the energy carried by an electromagnetic wave is true?
The energy is carried equally by the electric and magnetic fields.
The magnitude of the magnetic field component of a plane polarized electromagnetic wave traveling in vacuum is given by By = Bo sin[k z ñ ωt]. Which one of the following statements concerning this electromagnetic wave is true?
The wave is polarized in the x direction.
Which one of the following statements concerning the wavelength of an electromagnetic wave in a vacuum is true?
The wavelength is inversely proportional to the frequency of the wave.
Complete the following sentence: The various colors of visible light differ in
both frequency and wavelength.
Complete the following sentence: When electrons from a heated filament accelerate through vacuum toward a positive plate,
electromagnetic waves will be produced.
Which one of the following types of wave is fundamentally different than the other four?
sound waves
The most convincing evidence that electromagnetic waves are transverse waves is that
they can be polarized.
Which one of the following colors of visible light has the highest frequency?
violet
What is the correct order, beginning with shortest wavelength and extending to the longest wavelength, of the following colors in the visible light spectrum: blue, green, red, violet, and yellow?
violet, blue, green, yellow, red
A linearly polarized electromagnetic wave is sent through two sheets of polarizing material. The first sheet, A, is oriented so that its transmission axis makes an angle of 30∞ with respect to the incident electric field of the wave. The second sheet, B, is oriented so that its transmission axis makes an angle of 90∞ with the incident electric field of the wave. The incident beam has an electric field of peak magnitude E0 and average intensity S0. Suppose that A and B are interchanged so that the wave is first incident upon B. What is the average wave intensity after passing through both polarizing sheets?
zero
