Question 1

Transformers are the most efficient machines known.

Accepted Answer

Transformers are highly efficient machines that can convert high-voltage electricity to low-voltage electricity or vice versa with very little energy loss. They can operate at efficiencies of up to 99%, making them one of the most efficient machines known.

Question 2

The current in an inductor rises at a linear rate.

Accepted Answer

The current in an inductor does not rise at a linear rate due to the inductor's property of opposing changes in current, which causes the current to rise in an exponential manner, not linearly.

Question 3

In a shell transformer, the windings are placed around each end of the core material.

Accepted Answer

In a shell transformer, the windings are placed around the central limb or core, not around each end.

Question 4

A basic law concerning transformers is that all values of a transformer are ____ to its turns ratio.&#10;A) exponentially related&#10;B) inversely proportional&#10;C) logarithmically related&#10;D) proportional

Accepted Answer

All values of a transformer, such as voltage, current, and impedance, are directly proportional to its turns ratio. This means that if the turns ratio of a transformer is doubled, all values will also double.

Question 5

The amount of core material needed for a particular transformer is determined by the ____ of the transformer.&#10;A) efficiency&#10;B) power rating&#10;C) relative strength rating&#10;D) amount of magnetic coupling between the windings

Accepted Answer

The power rating of a transformer determines the amount of current and voltage it can handle, which in turn determines the size of the core needed to handle that power. A higher power rating requires a larger core to handle the increased magnetic flux.

Question 6

A ____ has a lower secondary voltage than primary voltage.&#10;A) step-down transformer&#10;B) resonant transformer&#10;C) constant voltage transformer&#10;D) planar transformer

Accepted Answer

A step-down transformer has a lower secondary voltage than primary voltage.

Question 7

The ____ is used to supply power to most homes and many businesses.&#10;A) distribution transformer&#10;B) auto transformer&#10;C) current transformer&#10;D) potential transformer

Accepted Answer

The distribution transformer is specifically designed to step down the high voltage from the power grid to a lower voltage suitable for use in homes and businesses.

Question 8

A special steel called silicon steel is often used in transformer cores to help reduce hysteresis loss.

Accepted Answer

Silicon steel is a common material used for transformer cores because it has high magnetic permeability and low hysteresis loss, which helps with energy efficiency.

Question 9

____ type cores are constructed by tightly winding one long continuous silicon steel tape into a spiral.&#10;A) Shell&#10;B) Horn&#10;C) Toroid&#10;D) E-I

Accepted Answer

Toroid type cores are constructed by tightly winding one long continuous silicon steel tape into a spiral to form a doughnut-shaped core.

Question 10

When a coil induces a voltage into itself, it is known as self-induction.

Accepted Answer

This is the definition of self-induction.

Deck 19: Isolation Transformers