Question 1

A changing magnetic field causes an electric field and a changing electric field causes a magnetic field.

Accepted Answer

A) True 
 B)False

Question 2

Situation 25.1
The following are positioned in sequence: A source of a beam of natural light of intensity Io;three ideal polarizers A,B,and C;and an observer.Polarizer axis angles are measured clockwise from the vertical,from the perspective of the observer.The axis angle of polarizer A is set at zero degrees (vertical),and the axis angle of polarizer C is set at 50 degrees.
-In Situation 25.1,polarizer B is set so that the beam intensity is zero at the observer.The two possible axis angle settings of polarizer B are:

Accepted Answer

A) 40° and 90° 
B) 40° and 130° 
C) 40° and 140° 
D) 90° and 130° 
E) 90° and 140° 
A) 40° and 90° 
B) 40° and 130° 
C) 40° and 140° 
D) 90° and 130° 
E) 90° and 140°

Question 3

If the peak electric field in an electromagnetic wave is 754 µV/m,what is the peak magnetic field for the same wave?

Accepted Answer

A) 2.51 × 10-12 T 
B) 7.53 T 
C) 7.54 × 10-4 T 
D) 3.98 × 1011 T 
A) 2.51 × 10-12 T 
B) 7.53 T 
C) 7.54 × 10-4 T 
D) 3.98 × 1011 T

Question 4

Situation 25.1
The following are positioned in sequence: A source of a beam of natural light of intensity Io;three ideal polarizers A,B,and C;and an observer.Polarizer axis angles are measured clockwise from the vertical,from the perspective of the observer.The axis angle of polarizer A is set at zero degrees (vertical),and the axis angle of polarizer C is set at 50 degrees.
-In Situation 25.1,polarizer B is set so that the beam intensity at the observer is a maximum.The axis angle of polarizer B is:

Accepted Answer

A) 0° 
B) 25° 
C) 50° 
D) 75° 
E) 100° 
A) 0° 
B) 25° 
C) 50° 
D) 75° 
E) 100°

Question 5

Find the energy (in eV)of an optical photon of frequency 5.15 x 1014 Hz.

Accepted Answer

A) 2.13 eV 
B) 1.30 eV 
C) 1.56 eV 
D) 2.62 eV 
A) 2.13 eV 
B) 1.30 eV 
C) 1.56 eV 
D) 2.62 eV

Question 6

-In the figure,one end of a bar is in contact with a circular rail and the other end is pivoted at P.A steady,uniform,magnetic field B is present.The bar rotates about P.The induced current through the resistor R is:

Accepted Answer

A) zero 
B) from a to b 
C) from b to a 
A) zero 
B) from a to b 
C) from b to a

Question 7

Two electromagnetic waves are traveling at the same speed.The wave with the higher wavelength

Accepted Answer

A) has a higher frequency than the other wave. 
B) has a lower frequency than the other wave. 
C) is traveling faster than the other wave. 
D) is traveling slower than the other wave. 
A) has a higher frequency than the other wave. 
B) has a lower frequency than the other wave. 
C) is traveling faster than the other wave. 
D) is traveling slower than the other wave.

Question 8

At a certain instant in time,an electromagnetic wave has   in the -z direction and   in the +y direction.In what direction does the wave propagate?

Accepted Answer

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

Question 9

A 2.0 m conductor is formed into a square and placed in the horizontal xy-plane.A magnetic field is oriented 30.0º above the horizontal with a strength of 9.0 T.What is the magnetic flux through the conductor?

Accepted Answer

A) 1.1 T ∙ m2 
B) 1.9 T ∙ m2 
C) 2.3 T ∙ m2 
D) 18 T ∙ m2 
A) 1.1 T ∙ m2 
B) 1.9 T ∙ m2 
C) 2.3 T ∙ m2 
D) 18 T ∙ m2

Question 10

-In the figure,a battery supplies a steady current to the solenoid on the left.The two solenoids are moving toward each other.The induced current through the resistor R is:

Accepted Answer

A) zero 
B) from a to b 
C) from b to a 
A) zero 
B) from a to b 
C) from b to a

Question 11

A circular conducting loop with a radius of 1.00 m and a small gap filled with a 10.0 Ω resistor is oriented in the xy-plane.If a magnetic field of 2.0 T,making an angle of 30º with the z-axis,increases to 9.0 T in 2.0 s,what is the magnitude of the current that will be caused to flow in the conductor?

Accepted Answer

A) 0.095 A 
B) 0.55 A 
C) 0.95 A 
D) 0.24 A 
A) 0.095 A 
B) 0.55 A 
C) 0.95 A 
D) 0.24 A

Question 12

What is the essential difference between microwaves and blue light?

Accepted Answer

A) One has an electric charge,the other does not. 
B) One undergoes refraction,the other does not. 
C) One is a form of radiation,the other is not. 
D) Blue light is a beam of photons.Microwaves are not photons. 
E) There is no essential difference in the nature of microwaves and blue light other than a difference in frequency and wavelength. 
A) One has an electric charge,the other does not. 
B) One undergoes refraction,the other does not. 
C) One is a form of radiation,the other is not. 
D) Blue light is a beam of photons.Microwaves are not photons. 
E) There is no essential difference in the nature of microwaves and blue light other than a difference in frequency and wavelength.

Question 13

In an electromagnetic wave,if the magnetic field points in the -x direction and the electric field points in the +z direction,the wave must be traveling in the +y direction.

Accepted Answer

A) True 
 B)False

Question 14

An 800 kHz radio signal is detected at a point 6.6 km distant from a transmitter tower.The electric field amplitude of the signal at that point is 780 mV/m.Assume that the signal power is radiated uniformly in all directions and that radio waves incident upon the ground are completely absorbed.The magnetic field amplitude of the signal at that point,in nT,is closest to:

Accepted Answer

A) 2.6 
B) 2.1 
C) 1.6 
D) 3.1 
E) 3.6 
A) 2.6 
B) 2.1 
C) 1.6 
D) 3.1 
E) 3.6

Question 15

-In the figure,a loop carries a steady current I.A bar is in contact with a pair of circular rails and rotates about the center of the loop.The induced current through the resistor R is:

Accepted Answer

A) zero 
B) from a to b 
C) from b to a 
A) zero 
B) from a to b 
C) from b to a

Question 16

-In the figure,a bar is in contact with a pair of parallel rails and is in motion with velocity ν.A uniform magnetic field is present.The induced current through the resistor R is:

Accepted Answer

A) zero 
B) from a to b 
C) from b to a 
A) zero 
B) from a to b 
C) from b to a

Question 17

-In the figure,a bar magnet moves away from the solenoid.The induced current through the resistor R is:

Accepted Answer

A) zero 
B) from a to b 
C) from b to a 
A) zero 
B) from a to b 
C) from b to a

Question 18

-In the figure,two solenoids are side by side.The switch S,initially open,is closed.The induced current through the resistor R is:

Accepted Answer

A) zero 
B) from a to b 
C) from b to a 
A) zero 
B) from a to b 
C) from b to a

Question 19

-In the figure,two parallel wires carry a current I in opposite directions.A rectangular loop is midway between the wires.The current I is decreasing.The induced current through the resistor R is:

Accepted Answer

A) zero 
B) from a to b 
C) from b to a 
A) zero 
B) from a to b 
C) from b to a

Question 20

If a coil stays at rest in a very large static magnetic field,no emf is induced in this coil.

Accepted Answer

A) True 
 B)False

Exam 25: Electromagnetic Induction and Electromagnetic Waves

A changing magnetic field causes an electric field and a changing electric field causes a magnetic field.

If the peak electric field in an electromagnetic wave is 754 µV/m,what is the peak magnetic field for the same wave?

Find the energy (in eV)of an optical photon of frequency 5.15 x 1014 Hz.

-In the figure,one end of a bar is in contact with a circular rail and the other end is pivoted at P.A steady,uniform,magnetic field B is present.The bar rotates about P.The induced current through the resistor R is:

Two electromagnetic waves are traveling at the same speed.The wave with the higher wavelength

At a certain instant in time,an electromagnetic wave has in the -z direction and in the +y direction.In what direction does the wave propagate?

A 2.0 m conductor is formed into a square and placed in the horizontal xy-plane.A magnetic field is oriented 30.0º above the horizontal with a strength of 9.0 T.What is the magnetic flux through the conductor?

-In the figure,a battery supplies a steady current to the solenoid on the left.The two solenoids are moving toward each other.The induced current through the resistor R is:

What is the essential difference between microwaves and blue light?

In an electromagnetic wave,if the magnetic field points in the -x direction and the electric field points in the +z direction,the wave must be traveling in the +y direction.

-In the figure,a loop carries a steady current I.A bar is in contact with a pair of circular rails and rotates about the center of the loop.The induced current through the resistor R is:

-In the figure,a bar is in contact with a pair of parallel rails and is in motion with velocity ν.A uniform magnetic field is present.The induced current through the resistor R is:

-In the figure,a bar magnet moves away from the solenoid.The induced current through the resistor R is:

-In the figure,two solenoids are side by side.The switch S,initially open,is closed.The induced current through the resistor R is:

-In the figure,two parallel wires carry a current I in opposite directions.A rectangular loop is midway between the wires.The current I is decreasing.The induced current through the resistor R is:

If a coil stays at rest in a very large static magnetic field,no emf is induced in this coil.

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Find the energy (in eV)of an optical photon of frequency 5.15 x 10¹⁴ Hz.