Transformers

Which of the following defines "transformer action"?

• The transfer of energy from one circuit to another through electromagnetic induction

• The transfer of energy from one circuit to another through electrostatic action

• The development of counter electromotive force where a magnetic field cuts a coil

• The development of a voltage across a coil as it cuts through a magnetic field

Which of the following is NOT a necessary element in a basic transformer?

• A core

• A primary winding

• A secondary winding

• A magnetic shield

What three materials are most commonly used for transformer cores?

• Copper, soft iron, and air

• Copper, soft iron, and steel

• Air, copper, and steel

• Air, soft iron, and steel

The two types of transformer cores most commonly used are the shell-core and the

• I-core

• E-core

• hollow-core

• laminated-core

What is the major difference between the primary and secondary windings of a transformer?

• The primary has more turns than the secondary

• The secondary has more insulation than the primary

• The primary is connected to the source; the secondary is connected to the load

• The primary is connected to the load; the secondary is connected to the source

What is the principal difference between a high-voltage transformer and a low-voltage transformer?

• A high-voltage transformer has more turns of wire than a low-voltage transformer

• A high-voltage transformer uses an air core, while a low-voltage transformer uses a shell-type core

• A high-voltage transformer uses a shell-type core, while a low-voltage transformer uses an air core

• A high-voltage transformer has more insulation between the layers of windings than does a low-voltage transformer

When the secondary of a transformer is NOT connected to a circuit, the transformer is said to be operating under which of the following conditions?

• Uncoupled

• No-load

• Loaded

• Open

What term applies to the current in the primary of a transformer that creates the magnetic field?

• Exciting current

• Primary current

• Magnetizing current

• Counter current

In the primary of a transformer, what opposes the current from the source?

• The impedance

• The forward emf

• The counter emf

• The exciting current

What is the source of the magnetic flux that develops secondary voltage in a transformer?

• Primary emf

• Secondary counter emf

• Primary exciting current

• Secondary exciting current