Question 1

Light of uniform intensity shines perpendicularly on a totally absorbing surface, fully illuminating the surface. If the area of the surface is decreased:

Accepted Answer

A)  the radiation pressure increases and the radiation force increases 
B)  the radiation pressure increases and the radiation force decreases 
C)  the radiation pressure stays the same and the radiation force increases 
D)  the radiation pressure stays the same and the radiation force decreases 
E)  the radiation preassure decreases and the radiation force decreases 
A)  the radiation pressure increases and the radiation force increases 
B)  the radiation pressure increases and the radiation force decreases 
C)  the radiation pressure stays the same and the radiation force increases 
D)  the radiation pressure stays the same and the radiation force decreases 
E)  the radiation preassure decreases and the radiation force decreases

Question 2

A company claims to have developed material that absorbs light energy without a transfer of momentum. Such material is:

Accepted Answer

A)  impossible 
B)  possible, but very expensive 
C)  inexpensive and already in common use 
D)  in use by NASA but is not commercially available 
E)  a breakthrough in high technology 
A)  impossible 
B)  possible, but very expensive 
C)  inexpensive and already in common use 
D)  in use by NASA but is not commercially available 
E)  a breakthrough in high technology

Question 3

Which of the following types of electromagnetic radiation travels at the greatest speed in vacuum?

Accepted Answer

A)  Radio waves 
B)  Visible light 
C)  X rays 
D)  Gamma rays 
E)  All of these travel at the same speed 
A)  Radio waves 
B)  Visible light 
C)  X rays 
D)  Gamma rays 
E)  All of these travel at the same speed

Question 4

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 5

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 6

Which of the following is NOT true for electromagnetic waves?

Accepted Answer

A)  they consist of changing electric and magnetic fields 
B)  they travel at different speeds in vacuum, depending on their frequency 
C)  they transport energy 
D)  they transport momentum 
E)  they can be reflected 
A)  they consist of changing electric and magnetic fields 
B)  they travel at different speeds in vacuum, depending on their frequency 
C)  they transport energy 
D)  they transport momentum 
E)  they can be reflected

Question 7

A vertical automobile radio antenna is sensitive to electric fields that are polarized:

Accepted Answer

A)  horizontally 
B)  in circles around the antenna 
C)  vertically 
D)  normal to the antenna in the forward direction 
E)  none of the above 
A)  horizontally 
B)  in circles around the antenna 
C)  vertically 
D)  normal to the antenna in the forward direction 
E)  none of the above

Question 8

The index of refraction of a substance is:

Accepted Answer

A)  the speed of light in the substance 
B)  the angle of refraction 
C)  the angle of incidence 
D)  the speed of light in vacuum divided by the speed of light in the substance 
E)  measured in radians 
A)  the speed of light in the substance 
B)  the angle of refraction 
C)  the angle of incidence 
D)  the speed of light in vacuum divided by the speed of light in the substance 
E)  measured in radians

Question 9

If the amplitude of the electric field in a plane electromagnetic wave is 100 V/m then the amplitude of the magnetic field is:

Accepted Answer

A)  3.3 * 10-7 T 
B)  6.7 * 10-7 T 
C)  0.27 T 
D)  8.0 *107 T 
E)  3.0*109 T 
A)  3.3 * 10-7 T 
B)  6.7 * 10-7 T 
C)  0.27 T 
D)  8.0 *107 T 
E)  3.0*109 T

Question 10

The rectangular metal tank shown is filled with an unknown liquid. The observer, whose eye is level with the top of the tank, can just see corner E. The index of refraction of this liquid is:

Accepted Answer

A)  1.75 
B)  1.67 
C)  1.50 
D)  1.33 
E)  1.25 
A)  1.75 
B)  1.67 
C)  1.50 
D)  1.33 
E)  1.25

Question 11

When an electromagnetic wave meets a reflecting surface, the direction taken by the reflected wave is determined by:

Accepted Answer

A)  the material of the reflecting surface 
B)  the angle of incidence 
C)  the index of the medium 
D)  the intensity of the wave 
E)  the wavelength 
A)  the material of the reflecting surface 
B)  the angle of incidence 
C)  the index of the medium 
D)  the intensity of the wave 
E)  the wavelength

Question 12

In a plane electromagnetic wave in vacuum, the ratio E/B of the amplitudes in SI units of the two fields is:

Accepted Answer

A)  the speed of light 
B)  an increasing function of frequency 
C)  a decreasing function of frequency 
D)    
E)    
A)  the speed of light 
B)  an increasing function of frequency 
C)  a decreasing function of frequency 
D)    
E)

Question 13

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 14

The theoretical upper limit for the frequency of electromagnetic waves is:

Accepted Answer

A)  just slightly greater than that of red light 
B)  just slightly less than that of blue light 
C)  the greatest x-ray frequency 
D)  none of the above (there is no upper limit) 
E)  none of the above (but there is an upper limit) 
A)  just slightly greater than that of red light 
B)  just slightly less than that of blue light 
C)  the greatest x-ray frequency 
D)  none of the above (there is no upper limit) 
E)  none of the above (but there is an upper limit)

Question 15

A clear sheet of polaroid is placed on top of a similar sheet so that their polarizing axes make an angle of 30$\degree$ with each other. The ratio of the intensity of emerging light to incident unpolarized light is:

Accepted Answer

A)  1:4 
B)  1:3 
C)  1:2 
D)  3:4 
E)  3:8 
A)  1:4 
B)  1:3 
C)  1:2 
D)  3:4 
E)  3:8

Question 16

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 17

Consider: radio waves (r), visible light (v), infrared (i), x-rays (x), and ultraviolet (u). In order of increasing frequency, they are:

Accepted Answer

A)  r, v, i, x, u 
B)  r, i, v, u, x 
C)  i, r, v, u, x 
D)  i, v, r, u, x 
E)  r, i, v, x, u 
A)  r, v, i, x, u 
B)  r, i, v, u, x 
C)  i, r, v, u, x 
D)  i, v, r, u, x 
E)  r, i, v, x, u

Question 18

Light with an intensity of 1 kW/m2 falls normally on a surface with an area of 1 cm2 and is completely absorbed. The force of the radiation on the surface is:

Accepted Answer

A)  1.0 * 10-4 N 
B)  3.3 * 10-11 N 
C)  1.7 * 10-10 N 
D)  3.3 * 10-10 N 
E)  6.7 *10-10 N 
A)  1.0 * 10-4 N 
B)  3.3 * 10-11 N 
C)  1.7 * 10-10 N 
D)  3.3 * 10-10 N 
E)  6.7 *10-10 N

Question 19

A plane electronmagnetic wave is travelling in the positive x direction. At the instant shown the electric field at the extremely narrow dashed rectangle is in the negative z direction and its magnitude is decreasing. Which diagram correctly shows the directions and relative magnitudes of the electric field at the edges of the rectangle?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 20

The relation n1sin$\theta$1 = n2 sin$\theta$2 which applies as a ray of light strikes an interface between two media, is known as:

Accepted Answer

A)  Gauss' law 
B)  Snell's law 
C)  Faraday's law 
D)  Cole's law 
E)  law of sines 
A)  Gauss' law 
B)  Snell's law 
C)  Faraday's law 
D)  Cole's law 
E)  law of sines

Exam 33: Electromagnetic Waves

Light of uniform intensity shines perpendicularly on a totally absorbing surface, fully illuminating the surface. If the area of the surface is decreased:

A company claims to have developed material that absorbs light energy without a transfer of momentum. Such material is:

Which of the following types of electromagnetic radiation travels at the greatest speed in vacuum?

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:

When light passes from air to glass, it bends:

Which of the following is NOT true for electromagnetic waves?

A vertical automobile radio antenna is sensitive to electric fields that are polarized:

The index of refraction of a substance is:

If the amplitude of the electric field in a plane electromagnetic wave is 100 V/m then the amplitude of the magnetic field is:

The rectangular metal tank shown is filled with an unknown liquid. The observer, whose eye is level with the top of the tank, can just see corner E. The index of refraction of this liquid is:

When an electromagnetic wave meets a reflecting surface, the direction taken by the reflected wave is determined by:

In a plane electromagnetic wave in vacuum, the ratio E/B of the amplitudes in SI units of the two fields is:

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

The theoretical upper limit for the frequency of electromagnetic waves is:

A clear sheet of polaroid is placed on top of a similar sheet so that their polarizing axes make an angle of 30 °\degree° with each other. The ratio of the intensity of emerging light to incident unpolarized light 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?

Consider: radio waves (r), visible light (v), infrared (i), x-rays (x), and ultraviolet (u). In order of increasing frequency, they are:

Light with an intensity of 1 kW/m2 falls normally on a surface with an area of 1 cm2 and is completely absorbed. The force of the radiation on the surface is:

The relation n1sin θ\thetaθ 1 = n2 sin θ\thetaθ 2 which applies as a ray of light strikes an interface between two media, is known as:

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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:

A clear sheet of polaroid is placed on top of a similar sheet so that their polarizing axes make an angle of 30 $\degree$ with each other. The ratio of the intensity of emerging light to incident unpolarized light is:

Light with an intensity of 1 kW/m² falls normally on a surface with an area of 1 cm² and is completely absorbed. The force of the radiation on the surface is:

The relation n₁sin $\theta$ ₁ = n₂ sin $\theta$ ₂ which applies as a ray of light strikes an interface between two media, is known as: