Transformers Quiz

What type of current do transformers use to give more scope for circuit and supply voltages?

• Direct current

• Alternating current

• Static current

• Pulsating current

Answer explanation

Transformers use Alternating current to provide more flexibility in circuit and supply voltages due to its ability to easily change voltage levels through electromagnetic induction.

What is the function of step-down transformers?

• To provide an extra-low voltage supply for small electrical appliances

• To produce voltages of up to 400 kV for power transmission purposes

• To convert direct current to alternating current

• To increase the voltage for industrial applications

Answer explanation

Step-down transformers function to provide an extra-low voltage supply for small electrical appliances.

What is the maximum voltage that large step-up transformers can produce for power transmission purposes?

• 100 kV

• 200 kV

• 300 kV

• 400 kV

Answer explanation

Large step-up transformers can produce a maximum voltage of 400 kV for power transmission purposes.

Why are transformers fundamental to the use of electricity?

• They convert electrical energy into mechanical energy

• They ensure the safe and efficient use of electricity

• They store electrical energy for later use

• They generate electricity from renewable sources

Answer explanation

Transformers ensure the safe and efficient use of electricity by stepping up or down voltage for transmission and distribution purposes.

What is the basic principle of a transformer?

• A single coil can induce a magnetic change in itself.

• Two independent coils can induce a magnetic change in each other.

• A magnetic core can induce a magnetic change in a coil.

• A single coil can induce a magnetic change in a magnetic core.

Answer explanation

Two independent coils can induce a magnetic change in each other.

What is static inductance?

• The magnetic flux of one coil inducing a magnetic change in the same coil.

• The magnetic flux of one coil inducing a magnetic change in the second coil.

• The magnetic flux of a magnetic core inducing a magnetic change in a coil.

• The magnetic flux of one coil inducing a magnetic change in a magnetic core.

Answer explanation

Static inductance refers to the magnetic flux of one coil inducing a magnetic change in the second coil, not in the same coil or a magnetic core.

What enhances the inductance in a transformer?

• When the two electrically separated coils are wound onto separate magnetic cores.

• When the two electrically separated coils are wound onto a common magnetic core.

• When the two electrically separated coils are wound without a magnetic core.

• When the two electrically separated coils are wound onto a non-magnetic core.

Answer explanation

When the two electrically separated coils are wound onto a common magnetic core, it enhances the inductance in a transformer.

What happens when an AC supply is applied to the primary coil of a transformer?

• The magnetic flux produced by the first coil remains constant.

• The magnetic flux produced by the first coil rotates and cuts through the secondary coil.

• The magnetic flux produced by the first coil decreases.

• The magnetic flux produced by the first coil increases.

Answer explanation

When an AC supply is applied to the primary coil of a transformer, the magnetic flux produced by the first coil rotates and cuts through the secondary coil, inducing a voltage in the secondary coil.

What type of configuration works with AC or chopped DC in a transformer?

• The field in the first coil remains constant.

• The field in the first coil rises and falls slowly.

• The field in the first coil rises and falls rapidly.

• The field in the first coil does not change.

Answer explanation

The field in the first coil rises and falls rapidly because AC or chopped DC causes rapid changes in the magnetic field, inducing voltage in the second coil of the transformer.

What is one of the main reasons why AC has been adopted for mains electricity supplies?

• It is easier to generate than DC.

• It is more economical to transmit electricity over long distances at high voltage.

• It is safer than DC.

• It requires less equipment.

Answer explanation

It is more economical to transmit electricity over long distances at high voltage.