Question 1

When transformers are constructed, the windings are often placed on separate legs to minimize flux leakage.

Accepted Answer

In transformer construction, the primary and secondary windings are typically wound around the same core leg to maximize magnetic coupling and minimize flux leakage.

Question 2

The coils of an air core transformer are wound on forms made of nonconducting materials.

Accepted Answer

Air core transformers have their coils wound on forms (or bobbins) made of nonconducting materials, such as plastic or ceramic, to provide structural support without affecting the magnetic field.

Question 3

The molecular motion caused by the magnetizing and demagnetizing of a transformer's core results in friction which produces heat. This heat loss plus the power loss caused by the magnetic lag is called the ____ loss.

A) phase
B) copper
C) friction
D) hysteresis

D

Accepted Answer

Hysteresis loss in a transformer is caused by the molecular motion due to the magnetizing and demagnetizing of the transformer's core, which produces heat. This, combined with the power loss due to magnetic lag, constitutes hysteresis loss.

Question 4

Air core transformers are ____.&#10;A) efficient&#10;B) inefficient&#10;C) as efficient as iron/steel core transformers&#10;D) about 30 percent efficient

Accepted Answer

Air core transformers are generally considered inefficient compared to iron or steel core transformers because the absence of a solid core results in a lower magnetic coupling between the coils.

Question 5

Transformers used for power distribution are wound on cores made of ____.&#10;A) iron or steel&#10;B) nonconducting materials&#10;C) aluminum&#10;D) antimony

Accepted Answer

Transformers used for power distribution have cores made of iron or steel because these materials have high magnetic permeability, which is essential for efficiently transferring electrical energy from one circuit to another through electromagnetic induction.

Question 6

A(n) ____ is used for installations where heavy loads are used infrequently or where it is apparent that future demand may require additional loading.&#10;A) autotransformer&#10;B) instrument transformer&#10;C) tapped transformer&#10;D) buck-boost transformer

Accepted Answer

A tapped transformer is used in installations where heavy loads are used infrequently or where future demand may require additional loading, as it allows for adjustments in voltage levels to accommodate varying load requirements.

Question 7

If a transformer increases the voltage, it is called a ____ transformer.&#10;A) step-up&#10;B) step-down&#10;C) buck-boost&#10;D) tapped

Accepted Answer

A step-up transformer increases the voltage from the primary to the secondary coil, hence the term "step-up".

Question 8

The type of material from which the core is made affects the efficiency of the transformer.

Accepted Answer

The core material influences the transformer's efficiency by affecting the magnetic flux, with materials like silicon steel reducing energy losses and improving efficiency.

Question 9

Small transformers, such as those used for doorbell and signal circuits, are usually very efficient.

Accepted Answer

The answer of Small transformers, such as those used for...

Question 10

If a transformer has a ratio of 10 to 1 (10:1), it is being used as a ____ transformer.&#10;A) step-up&#10;B) step-down&#10;C) buck-boost&#10;D) tapped

Accepted Answer

A transformer with a ratio of 10 to 1 (10:1) means that the primary voltage is 10 times higher than the secondary voltage, indicating it is reducing the voltage, hence it is a step-down transformer.

Question 11

A transformer's audible hum is a result of the laminations and windings vibrating as the magnetic field alternates.

Accepted Answer

The answer of A transformer's audible hum is a result...

Question 12

If a transformer's primary winding has 200 turns and the secondary winding has 600 turns, the turns ratio is ____.&#10;A) 1:4&#10;B) 4:1&#10;C) 1:3&#10;D) 3:1

Accepted Answer

The answer of If a transformer's primary winding has 200...

Question 13

What is one method of cooling a transformer?&#10;A) place in a tank of refrigerant&#10;B) place in an air-conditioned room&#10;C) place in a tank of water&#10;D) place in a tank of oil

Accepted Answer

The answer of What is one method of cooling a...

Question 14

The efficiency of a transformer may be as high as ____ percent.&#10;A) 85&#10;B) 90&#10;C) 99&#10;D) 100

Accepted Answer

The answer of The efficiency of a transformer may be...

Question 15

One method of transformer construction is to build up thin, flat sections called ____.&#10;A) intertwined coils&#10;B) pancake coils&#10;C) nested coils&#10;D) laminated coils

Accepted Answer

The answer of One method of transformer construction is to...

Deck 12: Transformers