Question 1

The order of increasing wavelength for blue (b), green (g), red (r), and yellow (y) light is:

Accepted Answer

A)  r, y, g, b 
B)  r, g, y, b 
C)  g, y, b, r 
D)  b, g, y, r 
E)  b, y, g, r 
A)  r, y, g, b 
B)  r, g, y, b 
C)  g, y, b, r 
D)  b, g, y, r 
E)  b, y, g, r

Question 2

An unpolarized beam of light has intensity I0. It is incident on two ideal polarizing sheets. The angle between the axes of polarization of these sheets is $\theta$. Find $\theta$0if the emerging light has intensity I0/4:

Accepted Answer

A)  sin-1(1/2) 
B)    
C)  cos-1(1/2) 
D)    
E)  tan-1(1/4) 
A)  sin-1(1/2) 
B)    
C)  cos-1(1/2) 
D)    
E)  tan-1(1/4)

Question 3

The electric field for a plane electromagnetic wave traveling in the +y direction is shown. Consider a point where   is in the +z direction. The   field is:

Accepted Answer

A)  in the +x direction and in phase with the   field 
B)  in the -x direction and in phase with the   field 
C)  in the +x direction and 1/4 wave out of phase with the   field 
D)  in the +z direction and in phase with the   field 
E)  in the +z direction and 1/4 wave out of phase with the   field 
A)  in the +x direction and in phase with the   field 
B)  in the -x direction and in phase with the   field 
C)  in the +x direction and 1/4 wave out of phase with the   field 
D)  in the +z direction and in phase with the   field 
E)  in the +z direction and 1/4 wave out of phase with the   field

Question 4

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 5

The critical angle for total internal reflection at a diamond-air interface is 25$\degree$. Suppose light is incident at an angle of $\theta$ with the normal. Total internal reflection will occur if the incident medium is:

Accepted Answer

A)  air and $\theta$ = 25$\degree$ 
B)  air and $\theta$ > 25$\degree$ 
C)  air and $\theta$  25$\degree$ 
A)  air and $\theta$ = 25$\degree$ 
B)  air and $\theta$ > 25$\degree$ 
C)  air and $\theta$  25$\degree$

Question 6

Evidence that electromagnetic waves carry momentum is:

Accepted Answer

A)  the tail of a comet points away from the sun 
B)  electron flow through a wire generates heat 
C)  a charged particle in a magnetic field moves in a circular orbit 
D)  heat can be generated by rubbing two sticks together 
E)  the Doppler effect 
A)  the tail of a comet points away from the sun 
B)  electron flow through a wire generates heat 
C)  a charged particle in a magnetic field moves in a circular orbit 
D)  heat can be generated by rubbing two sticks together 
E)  the Doppler effect

Question 7

An electromagnetic wave is transporting energy in the negative y direction. At one point and one instant the magnetic field is in the positive x direction. The electric field at that point and instant is:

Accepted Answer

A)  positive y direction 
B)  negative y direction 
C)  positive z direction 
D)  negative z direction 
E)  negative x direction 
A)  positive y direction 
B)  negative y direction 
C)  positive z direction 
D)  negative z direction 
E)  negative x direction

Question 8

A point source emits electromagnetic energy at a rate of 100 W. The intensity 10 m from the source is:

Accepted Answer

A)  10 W/m2 
B)  1.6 W/m2 
C)  1 W/m2 
D)  0.024W/m2 
E)  0.080 W/m2 
A)  10 W/m2 
B)  1.6 W/m2 
C)  1 W/m2 
D)  0.024W/m2 
E)  0.080 W/m2

Question 9

If nwater = 1.50 and nglass = 1.33, then total internal reflection at an interface between this glass and water:

Accepted Answer

A)  occurs whenever the light goes from glass to water 
B)  occurs whenever the light goes from water to glass 
C)  may occur when the light goes from glass to water 
D)  may occur when the light goes from water to glass 
E)  can never occur at this interface 
A)  occurs whenever the light goes from glass to water 
B)  occurs whenever the light goes from water to glass 
C)  may occur when the light goes from glass to water 
D)  may occur when the light goes from water to glass 
E)  can never occur at this interface

Question 10

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 11

A ray of light passes obliquely through a plate of glass having parallel faces. The emerging ray:

Accepted Answer

A)  is totally internally reflected 
B)  is bent more toward the normal than the incident ray 
C)  is bent further away from the normal than the incident ray 
D)  is parallel to the incident ray but displaced sideways 
E)  lies on the same straight line as the incident ray 
A)  is totally internally reflected 
B)  is bent more toward the normal than the incident ray 
C)  is bent further away from the normal than the incident ray 
D)  is parallel to the incident ray but displaced sideways 
E)  lies on the same straight line as the incident ray

Question 12

A pole stands in a river, half in and half out of the water. Another pole of the same length stands vertically on the shore at a place where the ground is level. The shadow cast by the pole in the river on the river bottom is:

Accepted Answer

A)  slightly longer than the shadow of the pole on land 
B)  much longer than the shadow of the pole on land 
C)  shorter than the shadow of the pole on land 
D)  shorter than the shadow of the pole on land if the sun is high and longer if the sun is low 
E)  the same length as the shadow of the pole on land 
A)  slightly longer than the shadow of the pole on land 
B)  much longer than the shadow of the pole on land 
C)  shorter than the shadow of the pole on land 
D)  shorter than the shadow of the pole on land if the sun is high and longer if the sun is low 
E)  the same length as the shadow of the pole on land

Question 13

Three polarizing sheets are placed in a stack with the polarizing directions of the first and third perpendicular to each other. What angle should the polarizing direction of the middle sheet make with the polarizing direction of the first sheet to obtain zero transmitted intensity when unpolarized light is incident on the stack?

Accepted Answer

A)  0 
B)  30 $\degree$ 
C)  45 $\degree$ 
D)  60 $\degree$ 
E)  all angles allow light to pass through 
A)  0 
B)  30 $\degree$ 
C)  45 $\degree$ 
D)  60 $\degree$ 
E)  all angles allow light to pass through

Question 14

The magnetic field in a sinusoidal light wave has an amplitude of 3.3 *10-7 T. The intensity of the wave is:

Accepted Answer

A)  1.7* 10-4 W/m2 
B)  13 W/m2 
C)  27 W/m2 
D)  1.0 *105 W/m2 
E)  4.0 * 1010 W/m2 
A)  1.7* 10-4 W/m2 
B)  13 W/m2 
C)  27 W/m2 
D)  1.0 *105 W/m2 
E)  4.0 * 1010 W/m2

Question 15

A ray of light in water (index n1) is incident on its surface (with air) at the critical angle. Some oil (index n2) is now floated on the water. The angle between the ray in the oil and the normal is:

Accepted Answer

A)  sin-1(1.00) 
B)  sin-1(1/n1) 
C)  sin-1(1/n2) 
D)  sin-1(n1/n2) 
E)  sin-1(n2/n1) 
A)  sin-1(1.00) 
B)  sin-1(1/n1) 
C)  sin-1(1/n2) 
D)  sin-1(n1/n2) 
E)  sin-1(n2/n1)

Question 16

The units of index of refraction are:

Accepted Answer

A)  m/s 
B)  s/m 
C)  radian 
D)  m/s2 
E)  none of these 
A)  m/s 
B)  s/m 
C)  radian 
D)  m/s2 
E)  none of these

Question 17

The diagram shows total internal reflection. Which of the following statements is NOT true?

Accepted Answer

A)  angle AON is the angle of incidence 
B)  angle AON = angle BON 
C)  angle AON must be the critical angle 
D)  the speed of light in medium II is greater than that in medium I 
E)  if angle AON were increased, there would still be total internal reflection 
A)  angle AON is the angle of incidence 
B)  angle AON = angle BON 
C)  angle AON must be the critical angle 
D)  the speed of light in medium II is greater than that in medium I 
E)  if angle AON were increased, there would still be total internal reflection

Question 18

Light with an intensity of 1 kW/m2 falls normally on a surface and is completely reflected. The radiation pressure is:

Accepted Answer

A)  1 kPa 
B)  3 *1011 Pa 
C)  1.7 * 10-6 Pa 
D)  3.3*10-6 Pa 
E)  6.7* 10-6 Pa 
A)  1 kPa 
B)  3 *1011 Pa 
C)  1.7 * 10-6 Pa 
D)  3.3*10-6 Pa 
E)  6.7* 10-6 Pa

Question 19

When the distance between a point source of light and a light meter is reduced from 6.0 m to 2.0 m, the intensity of illumination at the meter will be the original value multiplied by:

Accepted Answer

A)  3 
B)  9 
C)  1/3 
D)  1/9 
E)  1 
A)  3 
B)  9 
C)  1/3 
D)  1/9 
E)  1

Question 20

Radio waves of wavelength 300 m have a frequency of:

Accepted Answer

A)  10-6 kHz 
B)  500 kHz 
C)  1 MHz 
D)  9 MHz 
E)  108 kHz 
A)  10-6 kHz 
B)  500 kHz 
C)  1 MHz 
D)  9 MHz 
E)  108 kHz

Exam 33: Electromagnetic Waves

The order of increasing wavelength for blue (b), green (g), red (r), and yellow (y) light is:

An unpolarized beam of light has intensity I0. It is incident on two ideal polarizing sheets. The angle between the axes of polarization of these sheets is θ\thetaθ . Find θ\thetaθ 0if the emerging light has intensity I0/4:

The electric field for a plane electromagnetic wave traveling in the +y direction is shown. Consider a point where is in the +z direction. The field is:

An electromagnetic wave is generated by:

The critical angle for total internal reflection at a diamond-air interface is 25 °\degree° . Suppose light is incident at an angle of θ\thetaθ with the normal. Total internal reflection will occur if the incident medium is:

Evidence that electromagnetic waves carry momentum is:

An electromagnetic wave is transporting energy in the negative y direction. At one point and one instant the magnetic field is in the positive x direction. The electric field at that point and instant is:

A point source emits electromagnetic energy at a rate of 100 W. The intensity 10 m from the source is:

If nwater = 1.50 and nglass = 1.33, then total internal reflection at an interface between this glass and water:

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

A ray of light passes obliquely through a plate of glass having parallel faces. The emerging ray:

A pole stands in a river, half in and half out of the water. Another pole of the same length stands vertically on the shore at a place where the ground is level. The shadow cast by the pole in the river on the river bottom is:

The magnetic field in a sinusoidal light wave has an amplitude of 3.3 *10-7 T. The intensity of the wave is:

A ray of light in water (index n1) is incident on its surface (with air) at the critical angle. Some oil (index n2) is now floated on the water. The angle between the ray in the oil and the normal is:

The units of index of refraction are:

The diagram shows total internal reflection. Which of the following statements is NOT true?

Light with an intensity of 1 kW/m2 falls normally on a surface and is completely reflected. The radiation pressure is:

When the distance between a point source of light and a light meter is reduced from 6.0 m to 2.0 m, the intensity of illumination at the meter will be the original value multiplied by:

Radio waves of wavelength 300 m have a frequency of:

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Filters

An unpolarized beam of light has intensity I₀. It is incident on two ideal polarizing sheets. The angle between the axes of polarization of these sheets is $\theta$ . Find $\theta$ 0if the emerging light has intensity I₀/4:

The critical angle for total internal reflection at a diamond-air interface is 25 $\degree$ . Suppose light is incident at an angle of $\theta$ with the normal. Total internal reflection will occur if the incident medium is:

If n_water = 1.50 and n_glass = 1.33, then total internal reflection at an interface between this glass and water:

The magnetic field in a sinusoidal light wave has an amplitude of 3.3 *10^-⁷T. The intensity of the wave is:

A ray of light in water (index n₁) is incident on its surface (with air) at the critical angle. Some oil (index n₂) is now floated on the water. The angle between the ray in the oil and the normal is:

Light with an intensity of 1 kW/m² falls normally on a surface and is completely reflected. The radiation pressure is: