VRQ3 Introduction to Transformers

What is the primary function of a transformer?

• Convert AC voltage to DC voltage

• Change AC voltage to a higher or lower AC voltage

• Store electrical energy

• Generate electricity

Which of the following is not a function of a transformer?

• Changing AC voltage levels

• Converting AC to DC

• Operating on magnetic induction

• Working with AC voltages

Where is the load connected in a transformer?

• Secondary coil

• Primary coil

• Iron core

• AC supply

What is the effect of mutual inductance on the second coil when the current in the first coil changes?

• It remains unaffected

• It induces a current in the second coil

• It decreases the resistance in the second coil

• It increases the temperature of the second coil

What is the primary function of the transformer core?

• To conduct electricity

• To store energy

• To contain magnetic flux

• To increase voltage

What is the relationship between magnetic flux and voltage in a transformer?

• Inversely proportional

• Directly proportional

• No relationship

• Exponentially proportional

Answer explanation

In a transformer, the relationship between magnetic flux and voltage is governed by Faraday's Law of Electromagnetic Induction.

Faraday's Law states that the induced voltage in a coil is directly proportional to the rate of change of magnetic flux through the coil. Mathematically, it can be expressed as:

V=N (dΦ/dt)

What does Vs stand for in the context of the formula?

• A) Primary voltage in V

• B) Secondary voltage in V

• C) Primary coil turns

• D) Secondary coil turns

How does the number of turns in a coil affect the voltage according to the formula?

• A) More turns increase voltage

• B) More turns decrease voltage

• C) Turns have no effect on voltage

• D) Turns inversely affect voltage

What is the effect on the output voltage if the secondary coil has fewer turns than the primary coil?

• The output voltage is less than the input voltage

• The output voltage is equal to the input voltage

• The output voltage is more than the input voltage

• The output voltage is double the input voltage

What is the purpose of a step-up transformer?

• To increase the output voltage

• To decrease the output voltage

• To maintain the same voltage

• To convert AC to DC