Current flowing through a conductor develops a magnetic field flux of concentric circles expanding (perpendicular) outward from the conductor.
Select one:
True
False
The correct answer is 'True'.
If a student uses his or her left hand and points the thumb in the direction of current flow, the encircling fingers will give the direction of the magnetic field, when applying the left hand rule.
Select one:
True
False
The correct answer is 'True'.
If a person knows the direction of current flow in a conductor, how can he or she determine the direction of flux lines?
a. By applying Thevenin's Theorem
b. By the amount of resistance in the conductors
c. By using Kirchhoff's Law
d. By using the left hand rule for conductors
The correct answer is: By using the left hand rule for conductors
The strength of an electromagnetic field can be increased by increasing the ? conductor.
a. current flowing through the
b. resistance of the
c. voltage through the
d. any of the above
The correct answer is: current flowing through the
Which of the following current-carrying conductors show opposing magnetic fields?
a. a. only
b. a. and b.
c. b. only
d. a. and c.
e. c. only
f. a., b., and c.
The correct answer is: c. only
When a current carrying conductor is wound in a coil, a magnetic field is produced that will have a north and south pole.
Select one:
True
False
The correct answer is 'True'.
Increasing the number of loops will increase the ? of the magnetic field.
a. current
b. resistance
c. size
d. strength
The correct answer is: strength
What measurement is used to denote the magnetic field strength of a coil or electromagnet?
a. ampere-turns
b. relative motion
c. resistance
d. turns comparison
The correct answer is: ampere-turns
Wrapping the windings closer together will create a(n) ? magnetic field.
a. larger
b. smaller
c. stronger
d. tighter
The correct answer is: stronger
Adding a core of ferromagnetic material to the coil decreases the number of flux lines passing through the center of the coil, thereby decreasing the strength of the magnet.
Select one:
True
False
The correct answer is 'False'.
When a core is ? , there is no longer a change in the strength of the magnetic field when current through the coil is increased.
a. de-magnetized
b. energized
c. saturated
d. none of the above
The correct answer is: saturated
A concept of electromagnets is that it takes energy to maintain a magnet, but does not take energy to make a magnet.
Select one:
True
False
The correct answer is 'False'.
Which of the following best describes why soft iron is used for the core of an electromagnet?
a. Soft iron has low reluctance.
b. Soft iron is magnetic.
c. Soft iron will not become permanently magnetized.
d. b. and c.
e. a., b., and c.
The correct answer is: a., b., and c.
How can the north and south poles of a coil or electromagnet be determined?
a. Using Ohm's Law
b. Using Norton's Theorem
c. Using the left hand rule for coils
d. Using the right hand rule for coils
The correct answer is: Using the left hand rule for coils
The electrons move in a conductor because of the interaction between the magnetic field of the magnet and the magnetic field of the electrons. This motion causes a voltage to be induced in the conductor.
Select one:
True
False
The correct answer is 'True'.
Changing the direction of the conductor passing through the flux lines will change the ? .
a. amount of resistance in the circuit
b. amount of voltage at the source
c. direction of the current flow
d. all of the above
The correct answer is: direction of the current flow
In order for a magnetic field to induce a voltage into a conductor, there must be ? between the two.
a. a ground connection
b. magnetic resistance
c. relative motion
d. resistance
The correct answer is: relative motion
If a conductor is moving parallel with the flux lines, ? volts will be induced.
a. 0
b. 0.5
c. 1.3
d. 2.5
The correct answer is: 0