Question 1

The reflected load in a transformer is defined as the actual load as it appears to the source and results from:

Accepted Answer

A) theVoltage ratio. 
B) the power ratio. 
C) the current ratio. 
D) the turns ratio. 
A) theVoltage ratio. 
B) the power ratio. 
C) the current ratio. 
D) the turns ratio.

Question 2

$$\text { Figure } 14 < 1$$
-In Figure 14-1, if the primary to secondary turns ratio is 9:1 and a 1 $\mathrm { k } \Omega$ load resistor is placed in the secondary, the reflected resistance seen by the primary equals_______

Accepted Answer

A)  111$\Omega$ 
B)   162$\mathrm { k } \Omega$ 
C)  81 $\mathrm { k } \Omega$ 
D)   1 $\mathrm { k } \Omega$ 
A)  111$\Omega$ 
B)   162$\mathrm { k } \Omega$ 
C)  81 $\mathrm { k } \Omega$ 
D)   1 $\mathrm { k } \Omega$

Question 3

The turns ratio of a transformer (n)is defined as:

Accepted Answer

A) the number of turns in the secondary divided by the number of turns in the primary. 
B) the number of turns in the primary divided by the number of turns in the secondary. 
C) the number of turns in the primary multiplied by the number of turns in the secondary. 
D) the number of turns in the secondary multiplied by the number of turns in the primary. 
A) the number of turns in the secondary divided by the number of turns in the primary. 
B) the number of turns in the primary divided by the number of turns in the secondary. 
C) the number of turns in the primary multiplied by the number of turns in the secondary. 
D) the number of turns in the secondary multiplied by the number of turns in the primary.

Question 4

36 V of dc is applied to aW indings ratio of 1:2.W hat is the secondary voltage?

Accepted Answer

A) something slightly less than 72V ince transformers do have some loss 
B) 144V 
C) 72V 
D) none of the above 
A) something slightly less than 72V ince transformers do have some loss 
B) 144V 
C) 72V 
D) none of the above

Question 5

$$\text { Figure } 14 < 1$$
-What is the secondary current in Figure 14-1 with a     load resistor and 3:1 turns ratio?

Accepted Answer

A)   33 mARMS 
B)   400 mARMS 
C)   40 mARMS 
D)   330 mARMS 
A)   33 mARMS 
B)   400 mARMS 
C)   40 mARMS 
D)   330 mARMS

Question 6

A step-down transformer could have a primary-secondary turns ratio of 4:1.

Accepted Answer

A) True 
 B)False

Question 7

An autotransformer differs from most transformers in that:

Accepted Answer

A) it does not isolate the primaryVoltage from the secondary Voltage. 
B) primary and secondary Windings are the same. 
C) source current flows through both the Windings. 
D) all of these. 
A) it does not isolate the primaryVoltage from the secondary Voltage. 
B) primary and secondary Windings are the same. 
C) source current flows through both the Windings. 
D) all of these.

Question 8

$$\text { Figure } 14 < 1$$
-What is the primary current in Figure  14-1  if the turns ratio equals  1: 3  and Is equals  240 mA ?

Accepted Answer

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

Question 9

A transformer With a turns ratio of 1:7 is a step down transformer.

Accepted Answer

A) True 
 B)False

Question 10

The turns ratio required to match a  50$\Omega$  source to a  200$\Omega$  load is_____

Accepted Answer

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

Question 11

Transformers ________.

Accepted Answer

A) match the impedance of a source to the impedance of a load 
B) convert a higherVoltage into a lowerVoltage 
C) convert a lower current into a higher current 
D) all of these 
A) match the impedance of a source to the impedance of a load 
B) convert a higherVoltage into a lowerVoltage 
C) convert a lower current into a higher current 
D) all of these

Question 12

$$\text { Figure } 14 < 1$$
-In Figure 14-1, the primary to secondary turns ratio is changed to 2.5:1 and the secondary current equals  100 mA . What is the reflected resistance seen by the primary?

Accepted Answer

A)  3 $\mathrm { k } \Omega$ 
B)  5 $\mathrm { k } \Omega$ 
C)   1.2 $\mathrm { k } \Omega$ 
D)   2.5 $k \Omega$ 
A)  3 $\mathrm { k } \Omega$ 
B)  5 $\mathrm { k } \Omega$ 
C)   1.2 $\mathrm { k } \Omega$ 
D)   2.5 $k \Omega$

Question 13

To couple two circuits togetherW ith no change in either voltage or current, use ________.

Accepted Answer

A) a step-down transformer 
B) a step-up transformer 
C) a power transformer 
D) an isolation transformer 
A) a step-down transformer 
B) a step-up transformer 
C) a power transformer 
D) an isolation transformer

Question 14

$$\text { Figure } 14 < 1$$
-In Figure 14-1, if a load resistor of 75$$\Omega$$ is placed in the secondary circuit,What is the secondary current?

Accepted Answer

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

Question 15

$$\text { Figure } 14 < 1$$
-In Figure 14-1, if the primary to secondary turns ratio is changed to 4:1 and a 1 kΩ load resistor is in the secondary, the secondary current equals ________.

Accepted Answer

A) 30 mA 
B) 240 mA 
C) 120 mA 
D) 480 mA 
A) 30 mA 
B) 240 mA 
C) 120 mA 
D) 480 mA

Question 16

A transformer With a turns ratio of 1:1 is often used to isolate a load from a source.

Accepted Answer

A) True 
 B)False

Question 17

The efficiency of all transformers is very low.

Accepted Answer

A) True 
 B)False

Question 18

A transformer can be used as an impedance matching device.

Accepted Answer

A) True 
 B)False

Question 19

How can theW indings ratio be safely determined for an unmarked transformer?

Accepted Answer

A) StandardizedW
Ire color codes indicate Windings ratio. 
B) The turns ratio is the same as the ratio of primary resistance to secondary resistance ratio. 
C) Apply known lowVoltage ac to the primary and measure the secondary output. The ratio of
TheVoltages is the same as the Windings ratio. 
D) either A or C 
A) StandardizedW
Ire color codes indicate Windings ratio. 
B) The turns ratio is the same as the ratio of primary resistance to secondary resistance ratio. 
C) Apply known lowVoltage ac to the primary and measure the secondary output. The ratio of
TheVoltages is the same as the Windings ratio. 
D) either A or C

Question 20

$$\text { Figure } 14 < 1$$
-In Figure 14-1, if the secondary current is  50 mA , the reflected resistance seen by the primary equals_____

Accepted Answer

A)   7.2 $\mathrm { k } \Omega$ 
B)   14.4  $\mathrm { k } \Omega$ 
C)   800$\Omega$ 
D)   2.4$\mathrm { k } \Omega$ 
A)   7.2 $\mathrm { k } \Omega$ 
B)   14.4  $\mathrm { k } \Omega$ 
C)   800$\Omega$ 
D)   2.4$\mathrm { k } \Omega$

The reflected load in a transformer is defined as the actual load as it appears to the source and results from:

The turns ratio of a transformer (n)is defined as:

36 V of dc is applied to aW indings ratio of 1:2.W hat is the secondary voltage?

A step-down transformer could have a primary-secondary turns ratio of 4:1.

An autotransformer differs from most transformers in that:

$\text { Figure } 14 < 1 -What is the primary current in Figure 14-1 if the turns ratio equals 1: 3 and Is equals 240 mA ?$ $\text { Figure } 14 < 1$ -What is the primary current in Figure 14-1 if the turns ratio equals 1: 3 and Is equals 240 mA ?

A transformer With a turns ratio of 1:7 is a step down transformer.

The turns ratio required to match a 50 $\Omega$ source to a 200 $\Omega$ load is_____

Transformers ________.

To couple two circuits togetherW ith no change in either voltage or current, use ________.

$\text { Figure } 14 < 1 -In Figure 14-1, if a load resistor of 75 \Omega is placed in the secondary circuit,What is the secondary current?$ $\text { Figure } 14 < 1$ -In Figure 14-1, if a load resistor of 75 $\Omega$ is placed in the secondary circuit,What is the secondary current?

A transformer With a turns ratio of 1:1 is often used to isolate a load from a source.

The efficiency of all transformers is very low.

A transformer can be used as an impedance matching device.

How can theW indings ratio be safely determined for an unmarked transformer?

$\text { Figure } 14 < 1 -In Figure 14-1, if the secondary current is 50 mA , the reflected resistance seen by the primary equals_$ $\text { Figure } 14 < 1$ -In Figure 14-1, if the secondary current is 50 mA , the reflected resistance seen by the primary equals_

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

Rc Circuits

Inductors

Rl Circuits

Rlc Circuits and Resonance

Transformers

Regulators, Filters, and Op-Amps

Understanding Transducers, Sensors, and Conversion in Industrial Processes

Filters

Exam 14: Time Response of Reactive Circuits

The reflected load in a transformer is defined as the actual load as it appears to the source and results from:

Figure 14<1\text { Figure } 14 < 1 Figure 14<1 -In Figure 14-1, if the primary to secondary turns ratio is 9:1 and a 1 kΩ\mathrm { k } \OmegakΩ load resistor is placed in the secondary, the reflected resistance seen by the primary equals_______

The turns ratio of a transformer (n)is defined as:

36 V of dc is applied to aW indings ratio of 1:2.W hat is the secondary voltage?

Figure 14<1\text { Figure } 14 < 1 Figure 14<1 -What is the secondary current in Figure 14-1 with a 100 load resistor and 3:1 turns ratio?

A step-down transformer could have a primary-secondary turns ratio of 4:1.

An autotransformer differs from most transformers in that:

Figure 14<1\text { Figure } 14 < 1 Figure 14<1 -What is the primary current in Figure 14-1 if the turns ratio equals 1: 3 and Is equals 240 mA ?

A transformer With a turns ratio of 1:7 is a step down transformer.

The turns ratio required to match a 50 Ω\OmegaΩ source to a 200 Ω\OmegaΩ load is_____

Transformers ________.

Figure 14<1\text { Figure } 14 < 1 Figure 14<1 -In Figure 14-1, the primary to secondary turns ratio is changed to 2.5:1 and the secondary current equals 100 mA . What is the reflected resistance seen by the primary?

To couple two circuits togetherW ith no change in either voltage or current, use ________.

Figure 14<1\text { Figure } 14 < 1 Figure 14<1 -In Figure 14-1, if a load resistor of 75 Ω\OmegaΩ is placed in the secondary circuit,What is the secondary current?

Figure 14<1\text { Figure } 14 < 1 Figure 14<1 -In Figure 14-1, if the primary to secondary turns ratio is changed to 4:1 and a 1 kΩ load resistor is in the secondary, the secondary current equals ________.

A transformer With a turns ratio of 1:1 is often used to isolate a load from a source.

The efficiency of all transformers is very low.

A transformer can be used as an impedance matching device.

How can theW indings ratio be safely determined for an unmarked transformer?

Figure 14<1\text { Figure } 14 < 1 Figure 14<1 -In Figure 14-1, if the secondary current is 50 mA , the reflected resistance seen by the primary equals_____

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

Rc Circuits

Inductors

Rl Circuits

Rlc Circuits and Resonance

Transformers

Regulators, Filters, and Op-Amps

Understanding Transducers, Sensors, and Conversion in Industrial Processes

Filters

$\text { Figure } 14 < 1 -What is the primary current in Figure 14-1 if the turns ratio equals 1: 3 and Is equals 240 mA ?$ $\text { Figure } 14 < 1$ -What is the primary current in Figure 14-1 if the turns ratio equals 1: 3 and Is equals 240 mA ?

The turns ratio required to match a 50 $\Omega$ source to a 200 $\Omega$ load is_____

$\text { Figure } 14 < 1 -In Figure 14-1, if a load resistor of 75 \Omega is placed in the secondary circuit,What is the secondary current?$ $\text { Figure } 14 < 1$ -In Figure 14-1, if a load resistor of 75 $\Omega$ is placed in the secondary circuit,What is the secondary current?

$\text { Figure } 14 < 1 -In Figure 14-1, if the secondary current is 50 mA , the reflected resistance seen by the primary equals_$ $\text { Figure } 14 < 1$ -In Figure 14-1, if the secondary current is 50 mA , the reflected resistance seen by the primary equals_