Question 1

-What is the secondary voltage in Figure 14 -1 if the turns ratio is 4.5:1?

Accepted Answer

A)  26.7 V
B)  5.92 V
C)  540 V
D)  4.72 VE) A) and D)
F) A) and C)

Question 2

The relationship for the current ration (Isec/Ipri) in a transformer is:

Accepted Answer

A)  the same as the turns ratio (Nsec/Npri) .
B)  less than the turns ratio (Nsec/Npri) .
C)  more than the turns ratio (Nsec/Npri) .
D)  the inverse of the turns ratio (Nsec/Npri) .E) A) and B)
F) C) and D)

Question 3

The relationship for the impedance matching ratio (RL/Rpri) in a transformer is:

Accepted Answer

A)  opposite to the turns ratio (Nsec/Npri) squared.
B)  equal to the turns ratio (Nsec/Npri) squared.
C)  equal to the turns ratio (Nsec/Npri) .
D)  opposite to the turns ratio (Nsec/Npri) .E) C) and D)
F) B) and D)

Question 4

-What is the primary current in Figure 14 -1 if the turns ratio equals 1:3 and IS equals 240 mA?

Accepted Answer

A)  120 mA
B)  1.2 A
C)  60 mA
D)  720 mAE) B) and D)
F) A) and B)

Question 5

A center tap transformer has a connection at the midpoint of the secondary winding resulting in:

Accepted Answer

A)  two 180 degree out of phase secondary voltages.
B)  secondary voltages half that of a non -center tapped transformer with the same turns ratio.
C)  two equal magnitude secondary voltages.
D)  all of these.E) A) and B)
F) A) and C)

Question 6

The measured voltage on the secondary of a given transformer is 0 V. Which of the following could have caused this?

Accepted Answer

A)  open primary
B)  shorted load
C)  open secondary
D)  any of the aboveE) A) and D)
F) B) and C)

Question 7

The turns ratio required to match a 50 Ω source to a 200 Ω load is .

Accepted Answer

A)  2:1
B)  1:4
C)  1:2
D)  4:1E) B) and C)
F) A) and D) C

Question 8

The hysteresis loss in a transformer is .

Accepted Answer

A)  caused by the resistance of the wire
B)  caused by rapid reversal of the magnetic field
C)  caused by current flowing in the core
D)  another name for flux leakage lossE) None of the above
F) All of the above B

Question 9

When the turns ratio of a transformer is 1:10 and the primary AC voltage in 6 V, then the secondary voltage is _ _.

Accepted Answer

A)  36 V
B)  60 V
C)  6 V
D)  0.6 VE) A) and B)
F) A) and C)

Question 10

A transformer can be used as an impedance matching device.

Accepted Answer

A) True 
 B)False

Question 11

Which winding will have the lowest measured resistance in a transformer with four secondary windings?

Accepted Answer

A)  the 12 V secondary
B)  the 6.3 V secondary
C)  the 5 V secondary
D)  the 550 V secondaryE) A) and B)
F) All of the above

Question 12

- if a load resistor of 75 Ω is placed in the secondary circuit, what is the secondary current?

Accepted Answer

A)  533 mA
B)  4.8 A
C)  5.33 A
D)  16 AE) None of the above
F) All of the above

Question 13

The primary to secondary resistance should be relatively low.

Accepted Answer

A) True 
 B)False

Question 14

-What is the secondary current in Figure 14 -1 with a 50 Ω load resistor and 4:1 turns ratio?

Accepted Answer

A)  600 mA
B)  4.8 A
C)  1.66 A
D)  9.6 AE) A) and C)
F) A) and B) A

Question 15

What type transformer most likely has a 1:1 turns ratio?

Accepted Answer

A)  power
B)  isolation
C)  center tapped
D)  impedance matchingE) B) and C)
F) All of the above

Question 16

What is the likeliest way to fix a center -tapped transformer which outputs unequal voltages on each half of the secondary?

Accepted Answer

A)  Add some turns to the half with the lower voltage winding.
B)  Do not concern yourself; the customer will probably not notice the problem.
C)  Remove some turns from the half with the higher voltage winding.
D)  Replace the transformer.E) A) and B)
F) A) and C)

Question 17

When a 1 kΩ load resistor is connected across the secondary winding of a transformer with a turns ratio of 1:2, the source "sees" a reflected load of .

Accepted Answer

A)  250 Ω
B)  4 kΩ
C)  1 kΩ
D)  2 kΩE) B) and D)
F) B) and C)

Question 18

-What is the secondary voltage in Figure 14 -1 if the turns ratio is 7:1?

Accepted Answer

A)  8.59 VRMS
B)  840 VRMS
C)  17.1 VRMS
D)  420 VRMSE) B) and D)
F) A) and B)

Question 19

Transformer cores are made from laminated iron to reduce losses.

Accepted Answer

A) True 
 B)False

Question 20

For a transformer to operate properly, it must:

Accepted Answer

A)  be supplied with the proper AC signal.
B)  be connected to a load.
C)  work within its voltage, current and power ratings.
D)  all of these.E) C) and D)
F) A) and C)

Exam 14: Transformers

-What is the secondary voltage in Figure 14 -1 if the turns ratio is 4.5:1?

Correct AnswerverifiedShow Answer

The relationship for the current ration (Isec/Ipri) in a transformer is:

Correct AnswerverifiedShow Answer

The relationship for the impedance matching ratio (RL/Rpri) in a transformer is:

Correct AnswerverifiedShow Answer

-What is the primary current in Figure 14 -1 if the turns ratio equals 1:3 and IS equals 240 mA?

Correct AnswerverifiedShow Answer

A center tap transformer has a connection at the midpoint of the secondary winding resulting in:

Correct AnswerverifiedShow Answer

The measured voltage on the secondary of a given transformer is 0 V. Which of the following could have caused this?

Correct AnswerverifiedShow Answer

The turns ratio required to match a 50 Ω source to a 200 Ω load is .

Correct AnswerverifiedC

The hysteresis loss in a transformer is .

Correct AnswerverifiedB

When the turns ratio of a transformer is 1:10 and the primary AC voltage in 6 V, then the secondary voltage is _ _.

Correct AnswerverifiedShow Answer

A transformer can be used as an impedance matching device.

Correct AnswerverifiedShow Answer

Which winding will have the lowest measured resistance in a transformer with four secondary windings?

Correct AnswerverifiedShow Answer

- if a load resistor of 75 Ω is placed in the secondary circuit, what is the secondary current?

Correct AnswerverifiedShow Answer

The primary to secondary resistance should be relatively low.

Correct AnswerverifiedShow Answer

-What is the secondary current in Figure 14 -1 with a 50 Ω load resistor and 4:1 turns ratio?

Correct AnswerverifiedA

What type transformer most likely has a 1:1 turns ratio?

Correct AnswerverifiedShow Answer

What is the likeliest way to fix a center -tapped transformer which outputs unequal voltages on each half of the secondary?

Correct AnswerverifiedShow Answer

When a 1 kΩ load resistor is connected across the secondary winding of a transformer with a turns ratio of 1:2, the source "sees" a reflected load of .

Correct AnswerverifiedShow Answer

-What is the secondary voltage in Figure 14 -1 if the turns ratio is 7:1?

Correct AnswerverifiedShow Answer

Transformer cores are made from laminated iron to reduce losses.

Correct AnswerverifiedShow Answer

For a transformer to operate properly, it must:

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
C

Correct Answer
verified
B

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
A

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified