Deck 2: Magnetic Induction

Question 1

The polarity of the induced voltage is determined by the polarity of the magnetic field in relation to the direction of movement.

Answer 1

True

Question 2

When a resistive load is suddenly connected to a source of direct current, the current will instantly ____.

A) drop to its minimum value
B) rise to its maximum value
C) become erratic
D) stop flowing

Answer 2

B

Question 3

If a conductor cuts magnetic lines of flux at a rate of 1 V, a voltage of 1 Wb/s will be induced.

Answer 3

False

Question 4

The exponential curve can often be found in nature.

Question 5

A device often used to prevent induced voltage spikes when the current flow through an inductor is stopped is the ____.

A) closed switch
B) diode
C) electrode
D) iron-core inductor

Question 6

The important factors concerning magnetic induction are a magnetic field, movement, and polarity.

Question 7

A(n) ____ diode has a forward voltage drop of approximately 0.7 V regardless of the current flowing through it.

A) MOV
B) iron
C) oxide
D) silicon

Question 8

The time necessary for current in an inductor to reach its full Ohm's law value, called the R-L time constant, can be computed using the formula L = H / R.

Question 9

A coil has an inductance of one ____ when a current change of one ampere per second results in an induced voltage of one volt.

A) david
B) henry
C) weber
D) paul

Question 10

The principle of magnetic ____ states that whenever a conductor cuts through magnetic lines of flux, a voltage is induced into the conductor.

A) induction
B) conduction
C) reduction
D) fluctuation

Question 11

Iron-core inductors cannot be used for high-frequency applications because of ____ loss and hysteresis loss in the core material.

A) electrical current
B) phosphoresis
C) polarity
D) eddy current

Question 12

The exponential curve describes a rate of certain occurrences and is divided into four time constants.

Question 13

Each time constant in an exponential curve is equal to ____% of some value.

A) 20.0
B) 25.0
C) 33.3
D) 63.2

Question 14

A device that uses the collapsing magnetic field of an inductor to produce a very low voltage is the electric-fence charger.

Question 15

A device that can be used for spike suppression in either direct- or alternating-current circuits is the metal oxide varistor (MOV).

Question 16

Three factors determine the amount of voltage that will be induced in a conductor: the number of turns of wire, the strength of the magnetic field (flux density), and the ____ of the cutting action.

A) speed
B) movement
C) intensity
D) direction

Question 17

A(n) ____ occurs when the current flow through an inductor stops, and the current decreases at an exponential rate also.

A) voltage jolt
B) amp spike
C) wattage jolt
D) voltage spike

Question 18

Inductance is measured in units called the henry and is represented by the letter H.

Question 19

In magnetic measurement, ____ lines of flux are equal to one weber (Wb).

A) 100,000
B) 1,000,000
C) 10,000,000
D) 100,000,000

Question 20

The induced voltage is proportional to the rate of change of current (speed of the cutting action).