Question 1

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 loss 
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 loss B

Question 2

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) 4:1 
A) 2:1 
B) 1:4 
C) 1:2 
D) 4:1 C

Question 3

-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 A 
A) 600 mA 
B) 4.8 A 
C) 1.66 A 
D) 9.6 A A

Question 4

-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 V 
A) 26.7 V 
B) 5.92 V 
C) 540 V 
D) 4.72 V

Question 5

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

Accepted Answer

A) power 
B) isolation 
C) center tapped 
D) impedance matching 
A) power 
B) isolation 
C) center tapped 
D) impedance matching

Question 6

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 kΩ 
A) 250 Ω 
B) 4 kΩ 
C) 1 kΩ 
D) 2 kΩ

Question 7

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). 
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).

Question 8

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 above 
A) open primary 
B) shorted load 
C) open secondary 
D) any of the above

Question 9

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 secondary 
A) the 12 V secondary 
B) the 6.3 V secondary 
C) the 5 V secondary 
D) the 550 V secondary

Question 10

- 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 A 
A) 533 mA 
B) 4.8 A 
C) 5.33 A 
D) 16 A

Question 11

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). 
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).

Question 12

A transformer can be used as an impedance matching device.

Accepted Answer

A) True 
 B)False

Question 13

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 V 
A) 36 V 
B) 60 V 
C) 6 V 
D) 0.6 V

Question 14

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. 
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.

Question 15

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. 
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.

Question 16

The primary to secondary resistance should be relatively low.

Accepted Answer

A) True 
 B)False

Question 17

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. 
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.

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 VRMS 
A) 8.59 VRMS 
B) 840 VRMS 
C) 17.1 VRMS 
D) 420 VRMS

Question 19

Transformer cores are made from laminated iron to reduce losses.

Accepted Answer

A) True 
 B)False

Question 20

-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 mA 
A) 120 mA 
B) 1.2 A 
C) 60 mA 
D) 720 mA

The hysteresis loss in a transformer is .

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

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

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

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

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 .

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

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

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

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

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

A transformer can be used as an impedance matching device.

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

For a transformer to operate properly, it must:

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

The primary to secondary resistance should be relatively low.

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

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

Transformer cores are made from laminated iron to reduce losses.

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

Systems, Quantities, and Units

Voltage, Current, and Resistance

Ohms Law, Energy, and Power

Series Circuits

Parallel Circuits

Series-Parallel Circuits

Magnetism and Electromagnetism

Introduction to Alternating Current and Voltage

Capacitors

Rccircuits

Inductors

Rlcircuits

Rlccircuits and Resonance

Time Response of Reactive Circuits

Filters

Exam 14: Transformers

The hysteresis loss in a transformer is .

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

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

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

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

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 .

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

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

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

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

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

A transformer can be used as an impedance matching device.

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

For a transformer to operate properly, it must:

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

The primary to secondary resistance should be relatively low.

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

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

Transformer cores are made from laminated iron to reduce losses.

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

Systems, Quantities, and Units

Voltage, Current, and Resistance

Ohms Law, Energy, and Power

Series Circuits

Parallel Circuits

Series-Parallel Circuits

Magnetism and Electromagnetism

Introduction to Alternating Current and Voltage

Capacitors

Rccircuits

Inductors

Rlcircuits

Rlccircuits and Resonance

Time Response of Reactive Circuits

Filters