Deck 23: Mirrors and Lenses: Part A

Question 1

Determine the amount of energy carried in 50 m of a 3.5-mW He-Ne laser beam if the cross-sectional area of the beam is 5.0 × 10−⁶ m².

A) 2.9 × 10^-8 J
B) 5.8 × 10^-10 J
C) 0.024 J
D) 2.9 × 10^-10 J

Answer 1

5.8 × 10^-10 J

Question 2

What value of inductance should be used in a series circuit with a capacitor of 9.0 × 10−⁴ μF when designed to radiate a wavelength of 70 m? (c = 3.00 × 10⁸ m/s)

A) 3.8 × 10−⁴ mH
B) 1.9 × 10−⁴ mH
C) 3.8 mH
D) 1.5 × 10−³ mH

Answer 2

1.5 × 10−³ mH

Question 3

The electric field,
,in an electromagnetic wave is oriented in what direction with respect to its associated magnetic field,
?

A)
anti-parallel to

B)
perpendicular to

C)
at a 45° angle to

D)
parallel to

Answer 3

perpendicular to

Question 4

An electromagnetic wave with a peak electric field component of 7.5 × 10² N/C has what associated peak magnetic field value? (ε₀ = 8.85 × 10−¹² C²/N⋅m²,μ₀ = 4π × 10−⁷ T⋅m/A,and c = 3.00 × 10⁸ m/s)

A) 2.8 × 10−¹¹ T
B) 2.5 × 10^-6 T
C) 3.6 × 10¹⁰ T
D) 4.0 × 10−⁷ T

Question 5

How is the direction of propagation of an electromagnetic wave oriented relative to the associated And
Fields?

A) parallel to ,perpendicular to
B) parallel to ,perpendicular to
C) parallel to both and
D) perpendicular to both and

Question 6

What is the maximum value of the electric field E at 0.50 m from a 100 W light bulb radiating in all directions? (µ₀ = 4π × 10−⁷ T⋅m/A,c = 3.00 × 10⁸ m/s)

A) 3000 V/m
B) 155 V/m
C) 6000 V/m
D) 77 V/m

Question 7

Peak values for a neodymium-glass laser are 1200 J for 1 nanosecond.If the cross section of the laser beam is 1 cm²,what are the maximum values of E and B? (µ₀ = 4π × 10−⁷ T⋅m/A,c = 3.00 × 10⁸ m/s)

A) 3 × 10⁷ V/m,2 T
B) 2 × 10⁸ V/m,10 T
C) 1 × 10¹⁰ V/m,3 T
D) 3 × 10⁹ V/m,10 T

Question 8

The intensity of light from the Sun is 1.3 kW/m² at the distance of the Earth.The Earth's radius is 6.4 × 10⁶ m.If all the sunlight that hits the Earth were absorbed,what would be the magnitude of the resulting force on the Earth?

A) 0.0087 N
B) 1.8 × 10⁸ N
C) 5.6 × 10⁸ N
D) 87 N

Question 9

A 6.0-J pulse of light from a laser has what momentum?

A) Light does not have momentum because it doesn't have mass.
B) 3.0 × 10⁹ kg·m/s
C) 6.7 × 10^-9 kg·m/s
D) 2.0 × 10^-8 kg·m/s

Question 10

An electromagnetic wave with a peak magnetic field component of 7.3 × 10−⁷ T has an associated peak electric field component of what value? (μ₀ = 4π × 10−⁷ T⋅m/A,ε₀ = 8.85 × 10−¹² C²/N⋅m²,and c = 3.00 × 10⁸ m/s)

A) 45 N/C
B) 2.0 × 10−⁵ N/C
C) 2.2 × 10² N/C
D) 0.50 × 10−¹⁵ N/C

Question 11

A radio wave transmits 4.8 W/m² average power per unit area.What is the peak value of the associated magnetic field? (μ₀ = 4π × 10−⁷ T⋅m/A and c = 3.00 × 10⁸ m/s)

A) 1.0 × 10−⁷ T
B) 8.4 × 10−³ T
C) 2.0 × 10^-7 T
D) 30 T

Question 12

A solar cell has a light-gathering area of 10 cm² and produces 0.30 A at 0.80 V (DC)when illuminated with sunlight of intensity 1000 W/m².What is the efficiency of the solar cell?

A) 16%
B) 4%
C) 7%
D) 24%

Question 13

An ultraviolet light wave has a wavelength of 300 nm and speed of 1.8 × 10⁸ m/s through a transparent medium.What is the frequency of this wave in the medium? (1 nm = 10−⁹ m and c = 3.00 × 10⁸ m/s)

A) 7.0 × 10¹⁴ Hz
B) 6.0 × 10¹⁴ Hz
C) 6.3 × 10² Hz
D) 10 × 10¹⁴ Hz

Question 14

A radar pulse returns 2.0 × 10−⁴ seconds after it is sent out,having been reflected by an object.What is the distance between the radar antenna and the object? (c = 3.00 × 10⁸ m/s)

A) 3.0 × 10⁴ m
B) 4.5 × 10⁴ m
C) 9.0 × 10⁴ m
D) 6.0 × 10⁴ m

Question 15

A 100-kg spacecraft has a sail of area 300 m² that is absorbing sunlight of intensity 800 W/m².What is the resulting acceleration of the spacecraft?

A) 2.4 m/s²
B) 2.7 × 10^-6 m/s²
C) 8.0 × 10^-6 m/s²
D) 3.8 × 10^-5 m/s²

Question 16

An electromagnetic wave with a peak magnetic field component of 3.2 × 10−⁷ T carries what average power per unit area? (μ₀ = 4π × 10−⁷ T⋅m/A,ε₀ = 8.85 × 10−¹² C²/N⋅m²,and c = 3.00 × 10⁸ m/s)

A) 12 W/m²
B) 3.0 W/m²
C) 2.7 W/m²
D) 1.3 W/m²

Question 17

The Earth is 1.49 × 10¹¹ m from the Sun.If the solar radiation at the top of the Earth's atmosphere is 1340 W/m²,what is the total power output of the Sun?

A) 2.34 × 10³⁰ W
B) 3.74 × 10²⁶ W
C) 6.62 × 10²⁶ W
D) 7.48 × 10²⁷ W

Question 18

In order of decreasing frequency,which of the following is correct?

A) infrared,visible,ultraviolet,and gamma
B) gamma,ultraviolet,visible,and infrared
C) visible,radio,ultraviolet,and X-ray
D) visible,gamma,ultraviolet,and X-ray

Question 19

A radio wave signal,which transmits at a frequency of 10.4 MHz,has what wavelength? (c = 3.00 × 10⁸ m/s)

A) 28.8 m
B) 2.4 × 10−² m
C) 4.17 m
D) 41.7 m

Question 20

The human eye is sensitive to light with wavelength up to 750 nm.What is the frequency of radiation at this wavelength? (1 nm = 10−⁹ m and c = 3.00 × 10⁸ m/s)

A) 8.5 × 10⁸ Hz
B) 1.8 × 10⁸ Hz
C) 4.0 × 10¹⁴ Hz
D) 7.7 × 10¹⁴ Hz

Question 21

If the formula for the energy of a photon is E = hc​/λ,where h is a constant,c is the speed of light,and λ is the wavelength of the photon,which of the following is the formula for the momentum of a photon?

A) p = h/λ_p
B) p = hc²/λ_p
C) p = (h²c²/λ²)
D) p = h/λc_p

Question 22

An observer is moving in space toward a distant star at 200 km/s while the star is moving toward the observer at 400 km/s;the relative velocity being 600 km/s of approach.What relative change in frequency of the light from the star as seen by the observer? (The speed of light in space is 3.00 × 10⁵ km/s).

A) 0.067% increase
B) 0.20% decrease
C) 0.20% increase
D) 0.033% decrease

Question 23

Unpolarized light is passed through polarizer 1.The light then goes though polarizer 2 with its plane of polarization at 30.0° to that of polarizer 1.Polarizer 3 is placed after polarizer 2.Polarizer 3 has its plane of polarization at 30.0° to the plane of polarization of polarizer 2 and at 60.0° to that of polarizer 1.What fraction of the intensity of the original light gets though the last polarizer?

A) 0.707
B) 0.125
C) 0.281
D) 0.553

Question 24

A beam of plane polarized light is incident on 3 polarizers,the first with an axis at 30° to the original plane of polarization,the second at 60° to the original plane of polarization,and the third at 30° to the original plane of polarization.What angle does the plane of polarization of the transmitted light make with the original plane of polarization of the original beam?

A) 30°
B) 180°
C) 90°
D) The answer is not given.

Question 25

What is the wavelength of 200 MHz television EM waves? (c = 3 × 10⁸ m/s)

A) 9 km
B) 10 m
C) 1.5 m
D) 3 m

Question 26

Why are sound waves not polarizable?

A) Because they are not electromagnetic.
B) They are not transverse.
C) They are not longitudinal.
D) But this is readily possible!

Question 27

Find the frequency of X-rays of wavelength 2 × 10−¹¹ m.(c = 3 × 10⁸ m/s)

A) 3 × 10⁸ Hz
B) 1.5 × 10¹⁹ Hz
C) 3 × 10¹⁸ Hz
D) 6 × 10⁹ Hz

Question 28

Light not only has wavelike properties,but also has particle-like properties.What are these "particles" of light called?

A) quarks
B) wavicles
C) photons
D) etherons

Question 29

Star #1 is approaching the Earth with speed v.Star #2 is receding from the Earth with the same speed v.Measurements of the same spectral line from each of the stars show Doppler shifts in frequency.The light from which star will have the larger magnitude shift in frequency?

A) star #1
B) Both stars will have the same shift.
C) The value of the speed must be known before an answer can be found.
D) star #2

Question 30

Unpolarized light of intensity I₀ passes through two sheets of ideal polarizing material.If the transmitted intensity is 0.375I₀,what is the angle between the polarizers?

A) 22.5°
B) 60°
C) 30°
D) 45°

Question 31

A beam of polarized light of intensity I₀ passes through a sheet of ideal polarizing material.The polarization axis of the beam and the transmission axis of the sheet differ by 45°.What is the intensity of the emerging light?

A) 0.25I₀
B) 0.87I₀
C) 0.50I₀
D) 0.75I₀