Question 1

A ray of light passes through three media as shown. The speeds of light in these media obey:

Accepted Answer

A)  v1 > v2 > v3 
B)  v3 > v2 > v1 
C)  v3 > v1 > v2 
D)  v2 > v1 > v3 
E)  v1 > v3 > v2 
A)  v1 > v2 > v3 
B)  v3 > v2 > v1 
C)  v3 > v1 > v2 
D)  v2 > v1 > v3 
E)  v1 > v3 > v2

Question 2

The product   has the same units as:

Accepted Answer

A)  (velocity)2 
B)  (velocity)1/2 
C)  1/velocity 
D)  1/velocity2 
E)  1/velocity1/2 
A)  (velocity)2 
B)  (velocity)1/2 
C)  1/velocity 
D)  1/velocity2 
E)  1/velocity1/2

Question 3

The sun is about 1.5 * 1011 m away. The time for light to travel this distance is about:

Accepted Answer

A)  4.5 * 1018 s 
B)  8 s 
C)  8 min 
D)  8 hr 
E)  8 yr 
A)  4.5 * 1018 s 
B)  8 s 
C)  8 min 
D)  8 hr 
E)  8 yr

Question 4

The diagrams show four pairs of polarizing sheets, with the polarizing directions indicated by dashed lines. The two sheets of each pair are placed one behind the other and the front sheet is illuminated by unpolarized light. The incident intensity is the same for all pairs of sheets. Rank the pairs according to the intensity of transmitted light, least to greatest.

Accepted Answer

A)  1, 2, 3, 4 
B)  4, 2, 1, 3 
C)  2, 4, 3, 1 
D)  2, 4, 1, 3 
E)  3, 1, 4, 2 
A)  1, 2, 3, 4 
B)  4, 2, 1, 3 
C)  2, 4, 3, 1 
D)  2, 4, 1, 3 
E)  3, 1, 4, 2

Question 5

The index of refraction of a certain glass is 1.50. The sine of the critical angle for total internal reflection at a glass-air interface is:

Accepted Answer

A)  0.50 
B)  0.67 
C)  0.75 
D)  1.00 
E)  1.50 
A)  0.50 
B)  0.67 
C)  0.75 
D)  1.00 
E)  1.50

Question 6

If the electric field in a plane electromagnetic wave is given by Emsin[(3 *106/m-1)x -  $ \omega $t)], in SI the value of  $ \omega $is:

Accepted Answer

A)  0.01 rad/s 
B)  10 rad/s 
C)  100 rad/s 
D)  9 *1014 rad/s 
E)  9 *1016 rad/s 
A)  0.01 rad/s 
B)  10 rad/s 
C)  100 rad/s 
D)  9 *1014 rad/s 
E)  9 *1016 rad/s

Question 7

Radio waves differ from visible light waves in that radio waves:

Accepted Answer

A)  travel slower 
B)  have a higher frequency 
C)  travel faster 
D)  have a lower frequency 
E)  require a material medium 
A)  travel slower 
B)  have a higher frequency 
C)  travel faster 
D)  have a lower frequency 
E)  require a material medium

Question 8

Maxwell's equations predict that the speed of light in free space is:

Accepted Answer

A)  an increasing function of frequency 
B)  a decreasing function of frequency 
C)  independent of frequency 
D)  a function of the distance from the source 
E)  a function of the size of the source 
A)  an increasing function of frequency 
B)  a decreasing function of frequency 
C)  independent of frequency 
D)  a function of the distance from the source 
E)  a function of the size of the source

Question 9

An electromagnetic wave is generated by:

Accepted Answer

A)  any moving charge 
B)  any accelerating charge 
C)  only a charge with changing acceleration 
D)  only a charge moving in a circle 
E)  only a charge moving in a straight line 
A)  any moving charge 
B)  any accelerating charge 
C)  only a charge with changing acceleration 
D)  only a charge moving in a circle 
E)  only a charge moving in a straight line

Question 10

When light passes from air to glass, it bends:

Accepted Answer

A)  toward the normal without changing speed 
B)  toward the normal and slows down 
C)  toward the normal and speeds up 
D)  away from the normal and slows down 
E)  away from the normal and speeds up 
A)  toward the normal without changing speed 
B)  toward the normal and slows down 
C)  toward the normal and speeds up 
D)  away from the normal and slows down 
E)  away from the normal and speeds up

Question 11

The relation $\theta$incident = F1$\theta$reflected, which applies as a ray of light strikes an interface between two media, is known as:

Accepted Answer

A)  Faraday's law 
B)  Snell's law 
C)  Ampere's law 
D)  Cole's law 
E)  none of these 
A)  Faraday's law 
B)  Snell's law 
C)  Ampere's law 
D)  Cole's law 
E)  none of these

Question 12

In a stack of three polarizing sheets the first and third are crossed while the middle one has its axis at 45$\degree$to the axes of the other two. The fraction of the intensity of an incident unpolarized beam of light that is transmitted by the stack is:

Accepted Answer

A)  1/2 
B)  1/3 
C)  1/4 
D)  1/8 
E)  0 
A)  1/2 
B)  1/3 
C)  1/4 
D)  1/8 
E)  0

Question 13

At a certain point and a certain time the electric field of an electromagnetic wave is in the negative z direction and the magnetic field is in the positive y direction. Which of the following statements is true?

Accepted Answer

A)  Energy is being transported in the positive x direction but half a cycle later, when the electric field is in the opposite direction, it will be transported in the negative x direction 
B)  Energy is being transported in the positive x direction and half a cycle later, when the electric field is in the opposite direction, it will still be transported in the positive x direction 
C)  Energy is being transported in the negative x direction but half a cycle later, when the electric field is in the opposite direction, it will be transported in the positive x direction 
D)  Energy is being transported in the negative x direction and half a cycle later, when the electric field is in the opposite direction, it will still be transported in the negative x direction. 
E)  None of the above are true. 
A)  Energy is being transported in the positive x direction but half a cycle later, when the electric field is in the opposite direction, it will be transported in the negative x direction 
B)  Energy is being transported in the positive x direction and half a cycle later, when the electric field is in the opposite direction, it will still be transported in the positive x direction 
C)  Energy is being transported in the negative x direction but half a cycle later, when the electric field is in the opposite direction, it will be transported in the positive x direction 
D)  Energy is being transported in the negative x direction and half a cycle later, when the electric field is in the opposite direction, it will still be transported in the negative x direction. 
E)  None of the above are true.

Question 14

As light goes from one medium to another, it is bent away from the normal. Then:

Accepted Answer

A)  the speed of the light has increased 
B)  dispersion must occur 
C)  the second medium has a higher index of refraction 
D)  no change in speed has occurred 
E)  refraction has not occurred because refraction means a bending toward the normal 
A)  the speed of the light has increased 
B)  dispersion must occur 
C)  the second medium has a higher index of refraction 
D)  no change in speed has occurred 
E)  refraction has not occurred because refraction means a bending toward the normal

Question 15

Light from any ordinary source (such as a flame) is usually:

Accepted Answer

A)  unpolarized 
B)  plane polarized 
C)  circularly polarized 
D)  elliptically polarized 
E)  monochromatic 
A)  unpolarized 
B)  plane polarized 
C)  circularly polarized 
D)  elliptically polarized 
E)  monochromatic

Question 16

The diagram shows the passage of a ray of light from air into a substance X. The index of refraction of X is:

Accepted Answer

A)  0.53 
B)  0.88 
C)  1.9 
D)  2.2 
E)  3.0 
A)  0.53 
B)  0.88 
C)  1.9 
D)  2.2 
E)  3.0

Question 17

For linearly polarized light the plane of polarization is:

Accepted Answer

A)  perpendicular to both the direction of polarization and the direction of propagation 
B)  perpendicular to the direction of polarization and parallel to the direction of propagation 
C)  parallel to the direction of polarization and perpendicular to the direction of propagation 
D)  parallel to both the direction of polarization and the direction of propagation 
E)  none of the above 
A)  perpendicular to both the direction of polarization and the direction of propagation 
B)  perpendicular to the direction of polarization and parallel to the direction of propagation 
C)  parallel to the direction of polarization and perpendicular to the direction of propagation 
D)  parallel to both the direction of polarization and the direction of propagation 
E)  none of the above

Question 18

If the electric field in a plane electromagnetic wave is along the y axis and its component is given by Emsin(kx +  $ \omega $t), in SI units, then the magnetic field is along the z axis and its component is given by:

Accepted Answer

A)  (Em/c)cos(kx +  $ \omega $t) 
B)  -(Em/c)cos(kx +  $ \omega $t) 
C)  -(Em/c)sin(kx +  $ \omega $t) 
D)  Emcos(kx +  $ \omega $t) 
E)  (Em/c)sin(kx +  $ \omega $t) 
A)  (Em/c)cos(kx +  $ \omega $t) 
B)  -(Em/c)cos(kx +  $ \omega $t) 
C)  -(Em/c)sin(kx +  $ \omega $t) 
D)  Emcos(kx +  $ \omega $t) 
E)  (Em/c)sin(kx +  $ \omega $t)

Question 19

An electromagnetic wave is traveling in the positive x direction with its electric field along the z axis and its magnetic field along the y axis. The fields are related by:

Accepted Answer

A)   $\partial$E/ $\partial$x = $\mu$0$\varepsilon$0 $\partial$B/ $\partial$x 
B)   $\partial$E/ $\partial$x = $\mu$0$\varepsilon$0 $\partial$B/ $\partial$t 
C)   $\partial$B/ $\partial$x = $\mu$0$\varepsilon$0 $\partial$E/ $\partial$x 
D)  $\partial$B/ $\partial$x = $\mu$0$\varepsilon$0 $\partial$E/ $\partial$t 
E)   $\partial$B/ $\partial$x = -$\mu$0$\varepsilon$0 $\partial$E/ $\partial$t 
A)   $\partial$E/ $\partial$x = $\mu$0$\varepsilon$0 $\partial$B/ $\partial$x 
B)   $\partial$E/ $\partial$x = $\mu$0$\varepsilon$0 $\partial$B/ $\partial$t 
C)   $\partial$B/ $\partial$x = $\mu$0$\varepsilon$0 $\partial$E/ $\partial$x 
D)  $\partial$B/ $\partial$x = $\mu$0$\varepsilon$0 $\partial$E/ $\partial$t 
E)   $\partial$B/ $\partial$x = -$\mu$0$\varepsilon$0 $\partial$E/ $\partial$t

Exam 33: Electromagnetic Waves

A ray of light passes through three media as shown. The speeds of light in these media obey:

The product has the same units as:

The sun is about 1.5 * 1011 m away. The time for light to travel this distance is about:

The index of refraction of a certain glass is 1.50. The sine of the critical angle for total internal reflection at a glass-air interface is:

If the electric field in a plane electromagnetic wave is given by Emsin[(3 *106/m-1)x - ω \omega ω t)], in SI the value of ω \omega ω is:

Radio waves differ from visible light waves in that radio waves:

Maxwell's equations predict that the speed of light in free space is:

An electromagnetic wave is generated by:

When light passes from air to glass, it bends:

The relation θ\thetaθ incident = F1 θ\thetaθ reflected, which applies as a ray of light strikes an interface between two media, is known as:

In a stack of three polarizing sheets the first and third are crossed while the middle one has its axis at 45 °\degree° to the axes of the other two. The fraction of the intensity of an incident unpolarized beam of light that is transmitted by the stack is:

At a certain point and a certain time the electric field of an electromagnetic wave is in the negative z direction and the magnetic field is in the positive y direction. Which of the following statements is true?

As light goes from one medium to another, it is bent away from the normal. Then:

Light from any ordinary source (such as a flame) is usually:

The diagram shows the passage of a ray of light from air into a substance X. The index of refraction of X is:

For linearly polarized light the plane of polarization is:

If the electric field in a plane electromagnetic wave is along the y axis and its component is given by Emsin(kx + ω \omega ω t), in SI units, then the magnetic field is along the z axis and its component is given by:

An electromagnetic wave is traveling in the positive x direction with its electric field along the z axis and its magnetic field along the y axis. The fields are related by:

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The sun is about 1.5 * 10¹¹ m away. The time for light to travel this distance is about:

If the electric field in a plane electromagnetic wave is given by E_msin[(3 *10⁶/m^-¹)x - $\omega$ t)], in SI the value of $\omega$ is:

The relation $\theta$ _incident = F1 $\theta$ _reflected, which applies as a ray of light strikes an interface between two media, is known as:

In a stack of three polarizing sheets the first and third are crossed while the middle one has its axis at 45 $\degree$ to the axes of the other two. The fraction of the intensity of an incident unpolarized beam of light that is transmitted by the stack is:

The diagram shows the passage of a ray of light from air into a substance X. The index of refraction of X is: $The diagram shows the passage of a ray of light from air into a substance X. The index of refraction of X is:$

If the electric field in a plane electromagnetic wave is along the y axis and its component is given by E_msin(kx + $\omega$ t), in SI units, then the magnetic field is along the z axis and its component is given by: