Question 1

At a certain instant in time, the electric field of an electromagnetic wave in free space points in the -z direction, and the magnetic field points in the +y direction. In what direction is this wave traveling?

Accepted Answer

A)   +x direction
B)   -x direction
C)   +y direction
D)   -z direction
E)   +z directionF) A) and B)
G) B) and D)

Question 2

What is the frequency of 20-mm microwaves? (c = 3.0 × 108 m/s)

Accepted Answer

A)   100 MHz
B)   400 MHz
C)   15 GHz
D)   73 GHzE) All of the above
F) A) and C)

Question 3

Light of intensity S0 that is polarized horizontally passes through three ideal polarizers. The first and third are horizontal, but the second one is oriented at 0.39270  rad	ext{rad}rad  to the horizontal. In terms of S0, the intensity of the light that passes through the set of polarizers is closest to which one of the following choices?

Accepted Answer

A)   0.729 S0
B)   0.125 S0
C)   0.427 S0
D)   0.854 S0 E) B) and C)
F) B) and D)

Question 4

A flat rectangular coil with dimensions of 8.0 cm × 10 cm is dropped from a zero magnetic field position into a 1.4-T magnetic field in 0.10 s. The coil has 60 turns and is perpendicular to the magnetic field. What is the average induced emf in the coil as a result of this action?

Accepted Answer

A)   8.6 V
B)   2.4 V
C)   6.7 V
D)   3.6 V
E)   0 VF) A) and B)
G) B) and D)

Question 5

Which one of the following lists gives the correct order of the electromagnetic spectrum from low to high frequencies?

Accepted Answer

A)   radio waves, infrared, microwaves, ultraviolet, visible, x-rays, gamma rays
B)   radio waves, ultraviolet, x-rays, microwaves, infrared, visible, gamma rays
C)   radio waves, microwaves, infrared, visible, ultraviolet, x-rays, gamma rays
D)   radio waves, microwaves, visible, x-rays, infrared, ultraviolet, gamma rays
E)   radio waves, infrared, x-rays, microwaves, ultraviolet, visible, gamma raysF) A) and E)
G) A) and D)

Question 6

A 2.00-m long metal wire is formed into a square and placed in the horizontal xy-plane. A uniform magnetic field is oriented at 30° above the horizontal with a strength of 0.344 T. What is the magnetic flux through the square due to this field?

Accepted Answer

A)   0.0745 T ∙ m2
B)   0.172 T ∙ m2
C)   0.0430 T ∙ m2
D)   0.298 T ∙ m2E) A) and C)
F) All of the above

Question 7

A laser beam takes 24 ms to travel from a rocket to the reflective surface of a planet and back to the rocket. How far is the rocket from this planet's surface? (c = 3.0 × 108 m/s)

Accepted Answer

A)   2400 km
B)   1200 km
C)   1800 km
D)   3600 km
E)   4800 kmF) All of the above
G) B) and E)

Question 8

Unpolarized light is incident upon two ideal polarizing filters that do not have their transmission axes aligned. If  19%19 \%19%  of the light passes through this combination, what is the angle between the transmission axes of the two filters?

Accepted Answer

A)   52°
B)   72°
C)   0° D) A) and B)
E) None of the above

Question 9

In an electric furnace used for refining steel, the temperature is monitored by measuring the radiant power emitted through a small hole in the wall of the furnace, of area 0.5 cm2. This hole acts like a perfect blackbody radiator having the same temperature as the interior of the furnace. If the temperature of the furnace (and therefore of the hole)  is to be maintained at 1650°C, how much power will the hole radiate?

Accepted Answer

A)   20 W
B)   30 W
C)   40 W
D)   50 WE) B) and D)
F) B) and C)

Question 10

Which one of the following types of electromagnetic wave travels through space the fastest?

Accepted Answer

A)   radio waves
B)   infrared
C)   ultraviolet
D)   microwaves
E)   They all travel through space at the same speed.F) None of the above
G) C) and D)

Question 11

Polarized light of intensity S0 passes through an ideal polarizer. If the electric vector of the polarized light is horizontal what, in terms of the initial intensity S0, is the intensity of the light that passes through a polarizer if that polarizer is tilted 0.449  rad 	ext{rad }rad   from the horizontal?

Accepted Answer

A)   0.812 S0
B)   0.188 S0
C)   0.217 S0
D)   0.284 S0 E) None of the above
F) B) and D)

Question 12

A round flat conducting loop is placed perpendicular to a uniform 0.50 T magnetic field. If the area of the loop increases at a rate of 3.0 ×  10−310^{ - 3}10−3   m2m ^ { 2 }m2  /s, what is the induced emf in the loop?

Accepted Answer

A)   4.3 mV
B)   0 mV
C)   1.5 mV
D)   1.7 mV
E)   5.5 mV F) D) and E)
G) None of the above

Question 13

How much power does a sphere with a radius of 10 cm radiate into empty space if is has an emissivity of 1.0 and is kept at a temperature of 400 K? 
(σ = 5.67 × 10-8 W/m2 ∙ K4)

Accepted Answer

A)   60 W
B)   70 W
C)   180 W
D)   210 W
E)   360 WF) B) and D)
G) B) and C)

Question 14

Unpolarized light passes through three ideal polarizing filters. The first filter is oriented with a horizontal transmission axis, the second one has its transmission axis at 30° from the horizontal, and the third filter has a vertical transmission axis. What percent of the light gets through this combination?

Accepted Answer

A)   9.4%
B)   91%
C)   50%
D)   0%
E)   33%F) A) and B)
G) D) and E)

Question 15

What is the energy (in eV)  of an optical photon of frequency  6.43×1014 Hz6.43 	imes 10^{14} \mathrm {~Hz}6.43×1014 Hz  (h = 6.626 × 10-34 J ∙ s, 1 eV = 1.60 × 10-19 J)

Accepted Answer

A)   2.66 eV
B)   1.62 eV
C)   1.94 eV
D)   3.27 eV E) A) and B)
F) All of the above

Question 16

A flat coil having 160 turns, each with an area of 0.20 m2, is placed with the plane of its area perpendicular to a magnetic field of 0.40 T. The magnetic field changes uniformly from 0.40 T in the +x direction to 0.40 T in the -x direction in 2.0 s. If the resistance of the coil is 16 Ω, at what rate is power generated in the coil during this change?

Accepted Answer

A)   5.0 W
B)   10 W
C)   15 W
D)   20 WE) All of the above
F) B) and C)

Question 17

According to Lenz's law, the induced current in a circuit always flows to oppose the external magnetic flux through the circuit.

Accepted Answer

A) True 
 B)False

Question 18

A flat circular loop of radius 0.10 m is rotating in a uniform magnetic field of 0.20 T. Find the magnetic flux through the loop when the plane of the loop and the magnetic field vector are perpendicular.

Accepted Answer

A)   0 T ∙ m2
B)   3.1 × 10-3 T ∙ m2
C)   5.5 × 10-3 T ∙ m2
D)   6.3 × 10-3 T ∙ m2E) A) and C)
F) B) and C)

Question 19

It is known that birds can detect the earth's magnetic field, but the mechanism of how they do this is not known. It has been suggested that perhaps they detect a motional emf as they fly north to south, but it turns out that the induced voltages are small compared to the voltages normally encountered in cells, so this is probably not the mechanism involved. To check this out, calculate the induced voltage across the wingtips of a wild goose with a wingspan of  1.2 m1.2 \mathrm {~m}1.2 m   if it is flying directly south at  13 m/s13 \mathrm {~m} / \mathrm { s }13 m/s  at a point where the earth's magnetic field is 5.0 ×10-5 T directed downward from the horizontal by  40∘40 ^ { \circ }40∘

Accepted Answer

A)   0.50 mV
B)   0.60 mV
C)   0.78 mV
D)   0.060 mV
E)   0.25 mV F) B) and C)
G) A) and D)

Question 20

For an electromagnetic wave in free space having an electric field of amplitude E and a magnetic field of amplitude B, the ratio of B/E is equal to

Accepted Answer

A)   c
B)   c2
C)   1/c
D)   1/c2
E)    c\sqrt { c }cc-2.7,0,-7.17,-2.7,-13.5,-8c-5.8,-5.3,-9.5,-10,-9.5,-14c0,-2,0.3,-3.3,1,-4c1.3,-2.7,23.83,-20.7,67.5,-54c44.2,-33.3,65.8,-50.3,66.5,-51c1.3,-1.3,3,-2,5,-2c4.7,0,8.7,3.3,12,10s173,378,173,378c0.7,0,35.3,-71,104,-213c68.7,-142,137.5,-285,206.5,-429c69,-144,104.5,-217.7,106.5,-221l0 -0c5.3,-9.3,12,-14,20,-14H400000v40H845.2724s-225.272,467,-225.272,467s-235,486,-235,486c-2.7,4.7,-9,7,-19,7c-6,0,-10,-1,-12,-3s-194,-422,-194,-422s-65,47,-65,47zM834 80h400000v40h-400000z'/>​F) A) and D)
G) A) and C)

Exam 25: EM Induction and Em Waves

Correct Answer
verified

Correct Answer
verified

How much power does a sphere with a radius of 10 cm radiate into empty space if is has an emissivity of 1.0 and is kept at a temperature of 400 K? (σ = 5.67 × 10^-8 W/m² ∙ K⁴)

Correct Answer
verified

A round flat conducting loop is placed perpendicular to a uniform 0.50 T magnetic field. If the area of the loop increases at a rate of 3.0 × $10^{ - 3}$ $m ^ { 2 }$ /s, what is the induced emf in the loop?

Correct Answer
verified

A 2.00-m long metal wire is formed into a square and placed in the horizontal xy-plane. A uniform magnetic field is oriented at 30° above the horizontal with a strength of 0.344 T. What is the magnetic flux through the square due to this field?

Correct Answer
verified

Correct Answer
verified

Unpolarized light is incident upon two ideal polarizing filters that do not have their transmission axes aligned. If $19 \%$ of the light passes through this combination, what is the angle between the transmission axes of the two filters?

Correct Answer
verified

Correct Answer
verified

A flat rectangular coil with dimensions of 8.0 cm × 10 cm is dropped from a zero magnetic field position into a 1.4-T magnetic field in 0.10 s. The coil has 60 turns and is perpendicular to the magnetic field. What is the average induced emf in the coil as a result of this action?

Correct Answer
verified

For an electromagnetic wave in free space having an electric field of amplitude E and a magnetic field of amplitude B, the ratio of B/E is equal to

Correct Answer
verified

Which one of the following lists gives the correct order of the electromagnetic spectrum from low to high frequencies?

Correct Answer
verified

What is the frequency of 20-mm microwaves? (c = 3.0 × 10⁸ m/s)

Correct Answer
verified

A flat circular loop of radius 0.10 m is rotating in a uniform magnetic field of 0.20 T. Find the magnetic flux through the loop when the plane of the loop and the magnetic field vector are perpendicular.

Correct Answer
verified

What is the energy (in eV) of an optical photon of frequency $6.43 \times 10^{14} \mathrm {~Hz}$ (h = 6.626 × 10^-34 J ∙ s, 1 eV = 1.60 × 10^-19 J)

Correct Answer
verified

Correct Answer
verified

Which one of the following types of electromagnetic wave travels through space the fastest?

Correct Answer
verified

According to Lenz's law, the induced current in a circuit always flows to oppose the external magnetic flux through the circuit.

Correct Answer
verified

At a certain instant in time, the electric field of an electromagnetic wave in free space points in the -z direction, and the magnetic field points in the +y direction. In what direction is this wave traveling?

Correct Answer
verified

Correct Answer
verified

A laser beam takes 24 ms to travel from a rocket to the reflective surface of a planet and back to the rocket. How far is the rocket from this planet's surface? (c = 3.0 × 10⁸ m/s)

Correct Answer
verified

Exam 25: EM Induction and Em Waves

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

How much power does a sphere with a radius of 10 cm radiate into empty space if is has an emissivity of 1.0 and is kept at a temperature of 400 K? (σ = 5.67 × 10-8 W/m2 ∙ K4)

Correct AnswerverifiedShow Answer

A round flat conducting loop is placed perpendicular to a uniform 0.50 T magnetic field. If the area of the loop increases at a rate of 3.0 × 10−310^{ - 3}10−3 m2m ^ { 2 }m2 /s, what is the induced emf in the loop?

Correct AnswerverifiedShow Answer

A 2.00-m long metal wire is formed into a square and placed in the horizontal xy-plane. A uniform magnetic field is oriented at 30° above the horizontal with a strength of 0.344 T. What is the magnetic flux through the square due to this field?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Unpolarized light is incident upon two ideal polarizing filters that do not have their transmission axes aligned. If 19%19 \%19% of the light passes through this combination, what is the angle between the transmission axes of the two filters?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A flat rectangular coil with dimensions of 8.0 cm × 10 cm is dropped from a zero magnetic field position into a 1.4-T magnetic field in 0.10 s. The coil has 60 turns and is perpendicular to the magnetic field. What is the average induced emf in the coil as a result of this action?

Correct AnswerverifiedShow Answer

For an electromagnetic wave in free space having an electric field of amplitude E and a magnetic field of amplitude B, the ratio of B/E is equal to

Correct AnswerverifiedShow Answer

Which one of the following lists gives the correct order of the electromagnetic spectrum from low to high frequencies?

Correct AnswerverifiedShow Answer

What is the frequency of 20-mm microwaves? (c = 3.0 × 108 m/s)

Correct AnswerverifiedShow Answer

A flat circular loop of radius 0.10 m is rotating in a uniform magnetic field of 0.20 T. Find the magnetic flux through the loop when the plane of the loop and the magnetic field vector are perpendicular.

Correct AnswerverifiedShow Answer

What is the energy (in eV) of an optical photon of frequency 6.43×1014 Hz6.43 \times 10^{14} \mathrm {~Hz}6.43×1014 Hz (h = 6.626 × 10-34 J ∙ s, 1 eV = 1.60 × 10-19 J)

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which one of the following types of electromagnetic wave travels through space the fastest?

Correct AnswerverifiedShow Answer

According to Lenz's law, the induced current in a circuit always flows to oppose the external magnetic flux through the circuit.

Correct AnswerverifiedShow Answer

At a certain instant in time, the electric field of an electromagnetic wave in free space points in the -z direction, and the magnetic field points in the +y direction. In what direction is this wave traveling?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A laser beam takes 24 ms to travel from a rocket to the reflective surface of a planet and back to the rocket. How far is the rocket from this planet's surface? (c = 3.0 × 108 m/s)

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

How much power does a sphere with a radius of 10 cm radiate into empty space if is has an emissivity of 1.0 and is kept at a temperature of 400 K? (σ = 5.67 × 10^-8 W/m² ∙ K⁴)

Correct Answer
verified

A round flat conducting loop is placed perpendicular to a uniform 0.50 T magnetic field. If the area of the loop increases at a rate of 3.0 × $10^{ - 3}$ $m ^ { 2 }$ /s, what is the induced emf in the loop?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Unpolarized light is incident upon two ideal polarizing filters that do not have their transmission axes aligned. If $19 \%$ of the light passes through this combination, what is the angle between the transmission axes of the two filters?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

What is the frequency of 20-mm microwaves? (c = 3.0 × 10⁸ m/s)

Correct Answer
verified

Correct Answer
verified

What is the energy (in eV) of an optical photon of frequency $6.43 \times 10^{14} \mathrm {~Hz}$ (h = 6.626 × 10^-34 J ∙ s, 1 eV = 1.60 × 10^-19 J)

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

A laser beam takes 24 ms to travel from a rocket to the reflective surface of a planet and back to the rocket. How far is the rocket from this planet's surface? (c = 3.0 × 10⁸ m/s)

Correct Answer
verified