Question 1

What is the frequency of the most intense radiation from an object with temperature 100°C? The constant in Wien's law is 0.0029 m ∙ K. (c = 3.0 × 108 m/s)

Accepted Answer

A)  2.9 × 10-5 Hz 
B)  3.9 × 1013 Hz 
C)  1.0 × 1013 Hz 
D)  1.0 × 1011 Hz 
A)  2.9 × 10-5 Hz 
B)  3.9 × 1013 Hz 
C)  1.0 × 1013 Hz 
D)  1.0 × 1011 Hz

Question 2

A single-turn loop of wire, having a resistance of 8.00 Ω and a cross-sectional area 200 cm2, is perpendicular to a uniform magnetic field that increases steadily from 0.200 T to 2.800 T in 2.20 seconds. What is the magnitude of the induced current in the loop?

Accepted Answer

A)  2.95 A 
B)  3.18 A 
C)  0 A 
D)  3.18 mA 
E)  2.95 mA 
A)  2.95 A 
B)  3.18 A 
C)  0 A 
D)  3.18 mA 
E)  2.95 mA

Question 3

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 parallel.

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

Question 4

Radiation of a single frequency reaches the upper atmosphere of the earth with an intensity of 1350 W/m2. What is the maximum value of the electric field associated with this radiation? (c = 3.00 × 108 m/s, μ0 = 4π × 10-7 T ∙ m/A, ε0 = 8.85 × 10-12 C2/N ∙ m2)

Accepted Answer

A)  675.0 V/m 
B)  1604 V/m 
C)  1400 V/m 
D)  1350 V/m 
E)  1010 V/m 
A)  675.0 V/m 
B)  1604 V/m 
C)  1400 V/m 
D)  1350 V/m 
E)  1010 V/m

Question 5

For a certain electromagnetic wave in free space, at one instant the electric field vector points in the +z direction while the magnetic field vector points in the +x direction, as shown in the figure. In what direction is this wave traveling?

Accepted Answer

A)  +x 
B)  -x 
C)  +y 
D)  -y 
E)  +z 
A)  +x 
B)  -x 
C)  +y 
D)  -y 
E)  +z

Question 6

If the wavelength of a photon is doubled, what happens to its energy?

Accepted Answer

A)  It is reduced to one-half of its original value. 
B)  It stays the same. 
C)  It is doubled. 
D)  It is increased to four times its original value. 
E)  It is reduced to one-fourth of its original value. 
A)  It is reduced to one-half of its original value. 
B)  It stays the same. 
C)  It is doubled. 
D)  It is increased to four times its original value. 
E)  It is reduced to one-fourth of its original value.

Question 7

A conductor is formed into a flat loop that encloses an area of $1.0 \mathrm {~m} ^ { 2 }$ The plane of the loop is oriented at a 30.0° angle with the xy-plane. A uniform time-varying magnetic field is oriented parallel to the z-axis. If the emf induced in the loop is 25.0${~V}$ what is the rate at which the magnetic field strength is changing?

Accepted Answer

A)  29 T/s 
B)  22 T/s 
C)  50 T/s 
D)  13 T/s 
A)  29 T/s 
B)  22 T/s 
C)  50 T/s 
D)  13 T/s

Question 8

As shown in the figure, a region of space contains a uniform magnetic field. The magnitude of this field is 2.8 T, and it is directed straight into the plane of the page in the region shown. Outside this region the magnetic field is zero. A rectangular loop measuring 0.20 m by 0.60 m and having a resistance of 2 Ω is being pulled into the magnetic field by an external force, as shown.
(a) What is the direction (clockwise or counterclockwise) of the current induced in the loop?
(b) Calculate the magnitude of the external force Fext that is required to move the loop at a constant speed of 3.9 m/s.

Accepted Answer

(a) counte

Question 9

Two solenoids are close to each other, as shown in the figure, with the switch S open. When the switch is suddenly closed, which way will the induced current flow through the galvanometer in the left-hand solenoid?

Accepted Answer

A)  from left to right 
B)  from right to left 
C)  There will be no induced current through the galvanometer. 
A)  from left to right 
B)  from right to left 
C)  There will be no induced current through the galvanometer.

Question 10

A conducting rod of length ℓ= 25 cm is placed on a U-shaped metal wire that is connected to a lightbulb having a resistance of 8.0 Ω, as shown in the figure. The wire and the rod are in the plane of the page. A constant uniform magnetic field of strength 0.40 T is applied perpendicular to and into the paper. An applied external force pulls the rod to the right with a constant speed of 6.0 m/s. What is the magnitude of the emf induced in the rod?

Accepted Answer

A)  0.20 V 
B)  0.30 V 
C)  0.40 V 
D)  0.50 V 
E)  0.60 V 
A)  0.20 V 
B)  0.30 V 
C)  0.40 V 
D)  0.50 V 
E)  0.60 V

Question 11

How much time does it take a beam of light to travel 2.9 km through space. (c = 3.0 × 108 m/s)

Accepted Answer

A)  9.7 s 
B)  9.7 ms 
C)  9.7 μs 
D)  9.7 ns 
E)  9.7 ps 
A)  9.7 s 
B)  9.7 ms 
C)  9.7 μs 
D)  9.7 ns 
E)  9.7 ps

Question 12

How much energy is carried by a photon of light having frequency 110 GHz? (h = 6.626 × 10-34 J ∙ s)

Accepted Answer

A)  1.1 × 10-20 J 
B)  1.4 × 10-22 J 
C)  7.3 × 10-23 J 
D)  1.3 × 10-25 J 
A)  1.1 × 10-20 J 
B)  1.4 × 10-22 J 
C)  7.3 × 10-23 J 
D)  1.3 × 10-25 J

Question 13

A rectangular loop of wire that can rotate about an axis through its center is placed between the poles of a magnet in a magnetic field with a strength of 0.40 T, as shown in the figure. The length of the loop L is 0.16 m and its width w is 0.040 m. What is the magnetic flux through the loop when the plane of the loop is perpendicular to the magnetic field?

Accepted Answer

A)  13 × 10-3 T ∙ m2 
B)  2.6 × 103 T ∙ m2 
C)  0.80 T ∙ m2 
D)  2.6 × 10-3 T ∙ m2 
E)  0 T ∙ m2 
A)  13 × 10-3 T ∙ m2 
B)  2.6 × 103 T ∙ m2 
C)  0.80 T ∙ m2 
D)  2.6 × 10-3 T ∙ m2 
E)  0 T ∙ m2

Question 14

A light source radiates 60.0 W of single-wavelength sinusoidal light uniformly in all directions. What is the amplitude of the magnetic field of this light at a distance of 0.700 m from the bulb?(ε0 = 8.85 × 10-12 C2/N ∙ m2, μ0 = 4π × 10-7 T ∙ m/A, c = 3.0 × 108 m/s)

Accepted Answer

A)  1.76 × 10-7 T 
B)  2.02 × 10-7 T 
C)  2.22 × 10-7 T 
D)  2.86 × 10-7 T 
A)  1.76 × 10-7 T 
B)  2.02 × 10-7 T 
C)  2.22 × 10-7 T 
D)  2.86 × 10-7 T

Question 15

Increasing the brightness of a beam of light without changing its color will increase

Accepted Answer

A)  the number of photons per second traveling in the beam. 
B)  the energy of each photon. 
C)  the speed of the photons. 
D)  the frequency of the light. 
E)  the wavelength of the photons. 
A)  the number of photons per second traveling in the beam. 
B)  the energy of each photon. 
C)  the speed of the photons. 
D)  the frequency of the light. 
E)  the wavelength of the photons.

Question 16

A flat square coil of wire with 15 turns and an area of 0.40 m2 is placed with the plane of its area parallel to a magnetic field of 0.75 T. The coil is flipped so its plane is perpendicular to the magnetic field in a time of 0.050 s. What is the magnitude of the average induced emf in the coil?

Accepted Answer

A)  6.0 V 
B)  36 V 
C)  45 V 
D)  90 V 
A)  6.0 V 
B)  36 V 
C)  45 V 
D)  90 V

Question 17

How far does a beam of light travel through space in one 365-day year? (c = 3.0 × 108 m/s)

Accepted Answer

A)  80 × 1012 m 
B)  95 × 1014 m 
C)  30 × 108 m 
D)  20 × 1015 m 
E)  36 × 1016 m 
A)  80 × 1012 m 
B)  95 × 1014 m 
C)  30 × 108 m 
D)  20 × 1015 m 
E)  36 × 1016 m

Question 18

As shown in the figure, one end of a metal bar is in contact with a circular rail and the other end is pivoted at P. A steady uniform, magnetic field B into the page is present. As the bar rotates about point P in a clockwise direction, the direction of the induced current through the resistor R is

Accepted Answer

A)  from a to b. 
B)  from b to a. 
C)  No current is induced. 
A)  from a to b. 
B)  from b to a. 
C)  No current is induced.

Question 19

Light passes through three ideal polarizing sheets. Unpolarized light enters the first sheet and the resultant vertically polarized beam continues through the second sheet and third sheet. The second sheet has its transmission axis at 50° with respect to the first sheet, and the third sheet is at 70° with respect to the first sheet.
(a) What percent of the original intensity emerges from filter #1?
(b) What percent of the original intensity emerges from filter #2?
(c) What percent of the original intensity emerges from filter #3?

Accepted Answer

(a) 50% 
(

Question 20

As shown in the figure, a metal bar is in contact with a pair of metal parallel rails. A steady uniform magnetic field B, perpendicular to the plane of the rails and pointing outward from the page, is present. The bar is in downward motion with velocity of magnitude ν. The direction of the induced current through the resistor R is

Accepted Answer

A)  from a to b. 
B)  from b to a. 
C)  No current is induced. 
A)  from a to b. 
B)  from b to a. 
C)  No current is induced.

Exam 25: EM Induction and Em Waves

What is the frequency of the most intense radiation from an object with temperature 100°C? The constant in Wien's law is 0.0029 m ∙ K. (c = 3.0 × 108 m/s)

A single-turn loop of wire, having a resistance of 8.00 Ω and a cross-sectional area 200 cm2, is perpendicular to a uniform magnetic field that increases steadily from 0.200 T to 2.800 T in 2.20 seconds. What is the magnitude of the induced current in the loop?

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 parallel.

Radiation of a single frequency reaches the upper atmosphere of the earth with an intensity of 1350 W/m2. What is the maximum value of the electric field associated with this radiation? (c = 3.00 × 108 m/s, μ0 = 4π × 10-7 T ∙ m/A, ε0 = 8.85 × 10-12 C2/N ∙ m2)

For a certain electromagnetic wave in free space, at one instant the electric field vector points in the +z direction while the magnetic field vector points in the +x direction, as shown in the figure. In what direction is this wave traveling?

If the wavelength of a photon is doubled, what happens to its energy?

Two solenoids are close to each other, as shown in the figure, with the switch S open. When the switch is suddenly closed, which way will the induced current flow through the galvanometer in the left-hand solenoid?

How much time does it take a beam of light to travel 2.9 km through space. (c = 3.0 × 108 m/s)

How much energy is carried by a photon of light having frequency 110 GHz? (h = 6.626 × 10-34 J ∙ s)

A light source radiates 60.0 W of single-wavelength sinusoidal light uniformly in all directions. What is the amplitude of the magnetic field of this light at a distance of 0.700 m from the bulb?(ε0 = 8.85 × 10-12 C2/N ∙ m2, μ0 = 4π × 10-7 T ∙ m/A, c = 3.0 × 108 m/s)

Increasing the brightness of a beam of light without changing its color will increase

A flat square coil of wire with 15 turns and an area of 0.40 m2 is placed with the plane of its area parallel to a magnetic field of 0.75 T. The coil is flipped so its plane is perpendicular to the magnetic field in a time of 0.050 s. What is the magnitude of the average induced emf in the coil?

How far does a beam of light travel through space in one 365-day year? (c = 3.0 × 108 m/s)

As shown in the figure, one end of a metal bar is in contact with a circular rail and the other end is pivoted at P. A steady uniform, magnetic field B into the page is present. As the bar rotates about point P in a clockwise direction, the direction of the induced current through the resistor R is

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What is the frequency of the most intense radiation from an object with temperature 100°C? The constant in Wien's law is 0.0029 m ∙ K. (c = 3.0 × 10⁸ m/s)

A single-turn loop of wire, having a resistance of 8.00 Ω and a cross-sectional area 200 cm², is perpendicular to a uniform magnetic field that increases steadily from 0.200 T to 2.800 T in 2.20 seconds. What is the magnitude of the induced current in the loop?

Radiation of a single frequency reaches the upper atmosphere of the earth with an intensity of 1350 W/m². What is the maximum value of the electric field associated with this radiation? (c = 3.00 × 10⁸ m/s, μ₀ = 4π × 10^-7 T ∙ m/A, ε₀ = 8.85 × 10^-12 C²/N ∙ m²)

How much time does it take a beam of light to travel 2.9 km through space. (c = 3.0 × 10⁸ m/s)

How much energy is carried by a photon of light having frequency 110 GHz? (h = 6.626 × 10^-34 J ∙ s)

A light source radiates 60.0 W of single-wavelength sinusoidal light uniformly in all directions. What is the amplitude of the magnetic field of this light at a distance of 0.700 m from the bulb?(ε₀ = 8.85 × 10^-12 C²/N ∙ m², μ₀ = 4π × 10^-7 T ∙ m/A, c = 3.0 × 10⁸ m/s)

A flat square coil of wire with 15 turns and an area of 0.40 m² is placed with the plane of its area parallel to a magnetic field of 0.75 T. The coil is flipped so its plane is perpendicular to the magnetic field in a time of 0.050 s. What is the magnitude of the average induced emf in the coil?

How far does a beam of light travel through space in one 365-day year? (c = 3.0 × 10⁸ m/s)