Electromagnetic Induction and Waves Module 30: Electromagnetic Waves and Light Dynamic Study Module

Shown in the diagram below are the electric and magnetic components of an electromagnetic wave. In what direction is this wave traveling? An electromagnetic wave is shown on a coordinate system in three dimensions. The x-direction points towards the lower left-hand corner of the page. The y-direction points towards the top of the page. The z-direction points towards the lower right-hand corner. The electric field oscillates sinusoidally in the y-direction. It starts out pointing in the positive y-direction, then negative, positive, and negative. The magnetic field is oscillating sinusoidally in the z-direction. It starts out pointing in the negative z-direction, then positive, negative, positive. A. -x-direction B. -y-direction C. +y-direction D. +x-direction

-x-direction

If a beam of light has a frequency of 1.5 X 1012 Hz, what is its wavelength? A. 0.2 mm B. 0.2 micrometer C. 0.4 mm D. 0.1 mm

0.2 mm

If a beam of light has a frequency of 6 X 1017 Hz, what is its wavelength? A. 1 nm B. 0.5 nm C. 0.5 pm D. 0.25 nm

0.5 nm

Unpolarized light, with an intensity of I0, is incident on an ideal polarizer. A second ideal polarizer is immediately behind the first, and its axis of polarization is parallel to the first polarizer's. How much of the light will be transmitted through the system? A. 1/4 I0 B. 1/2 I0 C. start fraction start square root 2 end square root over 4 end fraction times I naught D. 1/8 I0

1/2 I0

Unpolarized light, with an intensity of I0, is incident on an ideal polarizer. A second ideal polarizer is immediately behind the first and its axis of polarization is oriented at an angle of 60° relative to the first polarizer's. How much of the light will be transmitted through the system? A. start fraction start square root 2 end square root over 4 end fraction times I naught (2/4Io) B. 1/2 I0 C. 1/8 I0 D. 1/4 I0

1/8 I0

If a beam of light has a wavelength of 1 micrometer, what is its frequency? A. 1.5 X 1014 Hz B. 3 X 1017 Hz C. 3 X 1011 Hz D. 3 X 1014 Hz

3 X 1014 Hz

A photon of light has a frequency of 8 X 1015 Hz. What is the energy of this photon of light in eV? A. 33 eV B. 66 eV C. 16.5 eV D. 5.3 X 10-18 eV

33 eV

What is the frequency of a photon of light with an energy of 1.66 eV? A. 2.5 X 1033 Hz B. 2 X 1014 Hz C. 4 X 1014 Hz D. 5 X 1033 Hz

4 X 1014 Hz

If a beam of light has a wavelength of 5 mm, what is its frequency? A. 6 X 1010 Hz B. 12 X 1010 Hz C. 3 X 1010 Hz D. 6 X 107 Hz

6 X 1010 Hz

What is the frequency of a photon of light with an energy of 3 eV? A. 4.53 X 1033 Hz B. 9.06 X 1033 Hz C. 1.45 X 1015 Hz D. 7.25 X 1014 Hz

7.25 X 1014 Hz

All objects are going to emit some amount of light, called thermal radiation, because they are made of charged particles that are always in motion. Which of the following statements about thermal radiation is correct? A. As an object's temperature is increased, it emits more light over the entire EM spectrum. B. As an object's temperature is decreased, it emits more light, but only in a part of the EM spectrum. C. As an object's temperature is increased, it emits more light, but only in a part of the EM spectrum. D. As an object's temperature is increased, it emits less light over the entire EM spectrum.

A. As an object's temperature is increased, it emits more light over the entire EM spectrum.

All objects are going to emit some amount of light, called thermal radiation, because they are made of charged particles that are always in motion. Which of the following statements about thermal radiation is correct? A. Objects that are very hot are going to tend to glow blue and in some cases white. B. Objects that are very hot are going to tend to glow red. C. Objects that are very hot are not actually going to emit enough visible light for people to see it. D. Objects that are very hot will only emit light in the ultraviolet spectrum, so they won't appear to glow.

A. Objects that are very hot are going to tend to glow blue and in some cases white.

All objects are going to emit some amount of light, called thermal radiation, because they are made of charged particles that are always in motion. Which of the following statements about thermal radiation is correct? A. Even if you increase an object's temperature, the object is not going to emit any light. B. As an object's temperature increases, the frequency at the peak of its thermal-emission spectrum increases. C. As an object's temperature increases, the frequency at the peak of its thermal-emission spectrum decreases. D. As an object's temperature increases, the frequency at the peak of its thermal-emission spectrum is constant.

B. As an object's temperature increases, the frequency at the peak of its thermal-emission spectrum increases.

An electromagnetic wave is shown in the diagram below. With which of the coordinate axes is the axis of polarization of the light aligned? An electromagnetic wave is shown on a coordinate system in three dimensions. The x-direction points towards the lower left-hand corner of the page. The y-direction points towards the top of the page. The z-direction points towards the lower right-hand corner. The electric field oscillates sinusoidally in the y-direction. It starts out pointing in the positive y-direction, then negative, positive, and negative. The magnetic field is oscillating sinusoidally in the z-direction. It starts out pointing in the negative z-direction, then positive, negative, positive. A. The light is not polarized B. y-axis C. z-axis D. x-axis

B. y-axis

On the electromagnetic spectrum there are many different kinds of light. Which of the kinds of light listed below has the longest wavelength? A. Gamma rays B. Ultraviolet C. Infrared D. Radio

D. Radio

On the electromagnetic spectrum there are many different kinds of light. Which of the kinds of light listed below has the most energy per photon? A. Ultraviolet B. Radio C. Gamma rays D. Infrared

Gamma rays

On the electromagnetic spectrum there are many different kinds of light. Which of the kinds of light listed below has typical frequencies that are close to, but lower than, visible light? A. Radio B. Ultraviolet C. Gamma rays D. Infrared

Infrared

In the diagram below are shown snapshots of the changing electric and magnetic field that make up a beam of light. Each frame has a time stamp, given in terms of the period of oscillation of the fields. In what direction is the beam of light moving? 5 coordinate systems are shown with the +y-direction towards the top of the page and the +z-direction towards the left side of the page. Each system shows the direction of the electric and magnetic components of an electromagnetic field during a fraction of the period of oscillation of the electromagnetic wave. System 1: At t = 0 the electric field points in the -y-direction and the magnetic field points in the +z-direction. System 2: At t = T/8 the electric and magnetic fields point in the same directions as at t = 0 with decreased magnitudes. System 3: At t = 2T/8 the magnitudes of both the electric and magnetic fields are zero. System 4: At t = 3T/8 the electric field points in the +y-direction and the magnetic field points in the -z-direction with the same magnitudes as at t = T/8. System 5: At t = 4T/8 the electric and magnetic fields point in the same directions as at t = 3T/8 with increased magnitudes. A. -z-direction B. Into the page (-x-direction) Out of the page (+x-direction)C. D. +z-direction

Into the page (-x-direction)

If you increase the distance between yourself and a point source of light by a factor of 3, by how much does the intensity of the light you see emanating from that source change? A. It decreases by a factor of 9. B. It decreases by a factor of 3. C. It increases by a factor of 3. D. It increases by a factor of 9.

It decreases by a factor of 9

If you decrease the distance between yourself and a point source of light by a factor of 4, by how much does the intensity of the light you see emanating from that source change? A. It increases by a factor of 16. B. It increases by a factor of 4. C. It decreases by a factor of 16. D. It decreases by a factor of 4.

It increases by a factor of 16.

If you decrease the distance between yourself and a point source of light by a factor of 2, by how much does the intensity of the light you see emanating from that source change? A. It increases by a factor of 2. B. It decreases by a factor of 2. C. It increases by a factor of 4. D. It decreases by a factor of 4.

It increases by a factor of 4.

Unpolarized light, with an intensity of I0, is incident on an ideal polarizer. A second ideal polarizer is immediately behind the first, and its axis of polarization is perpendicular to the first polarizer's. How much of the light will be transmitted through the system? A. 1/4 I0 B. 1/8 I0 C. No light will be transmitted. D. 1/2 I0

No light will be transmitted.

In the diagram below are shown snapshots of the changing electric and magnetic field that make up a beam of light. Each frame has a time stamp, given in terms of the period of oscillation of the fields. In what direction is the beam of light moving? 5 coordinate systems are shown with the +y-direction towards the top of the page and the +z-direction towards the left side of the page. Each system shows the direction of the electric and magnetic components of an electromagnetic field during a fraction of the period of oscillation of the electromagnetic wave. System 1: At t = 0, the electric field points in the +y-direction and the magnetic field points in the +z-direction. System 2: At t = T/8 the electric and magnetic fields point in the same directions as at t = 0 with have decreased magnitudes. System 3: At t = 2T/8 the magnitudes of both the electric and magnetic fields are zero. System 4: At t = 3T/8 the electric field points in the -y-direction and the magnetic field points in the -z-direction with the same magnitudes as at t = T/8. System 5: At t = 4T/8 the electric field and magnetic fields point in the same directions as at t = 3T/8 with decreased magnitudes. A. -z-direction B. Into the page (-x-direction) C. Out of the page (+x-direction) D. +z-direction

Out of the page (+x-direction)

An electromagnetic wave is shown in the diagram below. With which of the coordinate axes is the axis of polarization of the light aligned? 5 coordinate systems are shown with the +y-direction towards the top of the page and the +z-direction towards the left side of the page. Each system shows the direction of the electric and magnetic components of an electromagnetic field during a fraction of the period of oscillation of the electromagnetic wave. System 1: At t = 0 the electric field points in the -y-direction and the magnetic field points in the +z-direction. System 2: At t = T/8 the electric and magnetic fields point in the same directions as at t = 0 with decreased magnitudes. System 3: At t = 2T/8 the magnitudes of both the electric and magnetic fields are zero. System 4: At t = 3T/8 the electric field points in the +y-direction and the magnetic field points in the -z-direction with the same magnitudes as at t = T/8. System 5: At t = 4T/8 the electric and magnetic fields point in the same directions as at t = 3T/8 with increased magnitudes. A. z-axis B. x-axis C. The light is not polarized. D. y-axis

y-axis

An electromagnetic wave is shown in the diagram below. With which of the coordinate axes is the axis of polarization of the light aligned? A. y-axis B. The light is not polarized. C. z-axis D. x-axis

z-axis