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• 1. AC Theory Modules
• 2. Capacitors
• 3. Inductors
• 4. DC Transients
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• 8. Filters & Wave shaping
• 9. LCR Series Circuits
• 10. LCR Parallel Circuits
• 11. Transformers

Module 11.6

Transformers Quiz

Try our quiz, based on the information you can find in Module 11. Submit your answers and see how many you get right. If you get answers wrong, just follow the hints on the answers page to find the right answer and learn more about transformers as you go.

1.

What is the primary voltage applied to the transformer illustrated in Fig 11.6.1?

• a) 90V
• b) 18V
• c) 62.5V
• d) 0.4V

2.

What is the value of current flowing through the resistor R in Fig 11.6.2?

• a) 240mA
• b) 6.7mA
• c) 18mA
• d) 125mA

3.

Which solution from the following may be used to overcome hysteresis losses in power transformers?

• a) Low resistivity copper windings.
• b) Low reluctance steel cores.
• c) Laminated steel cores.
• d) Soft Iron cores.

4.

Flux linkage between primary and secondary windings of a transformer is proportional to which of the following?

• a) Cross sectional area of the core and the length of the flux path.
• b) Cross sectional area and Permeability of the core
• c) c) Cross sectional area and Reluctance of the core.
• d) Permeability of the core and the length of the flux path.

5.

Refer to the diagram of an autotransformer in Fig. 11.6.3.
If the voltage across A and D is 230V, what will be (approximately) the voltage across A and B?

• a) 20V
• b) 4.5V
• c) 9.6V
• d) 11.4V

6.

What will be the approximate turns ratio of a transformer matching a microphone of 60Ω impedance to the 47kΩ input impedance of an amplifier?

• a) 1:108
• b) 1:78
• c) 1:35
• d) 1:28

7.

Which of the following would be the most important property of the material, used for an electromagnetic shield around a RF transformer?

• a) Low reluctance.
• b) Low resistivity.
• c) Low conductance.
• d) Low permeability.

8.

Refer to the diagram of a transformer having a continuously wound, centre tapped secondary winding in Fig. 11.6.4:
What is the relationship between voltages across AB and BC when B is used as the common terminal?

• a) AB and BC are equal and in anti phase.
• b) AB is twice BC and in phase.
• c) AB is half BC and in phase.
• d) AB and BC are equal and in phase.

9.

Refer to Fig 11.6.4:
What is the voltage between A and C when B is connected to 0V?

• a) 30V
• b) 15V
• c) 7.5V
• d) 0V

10.

How are eddy current losses reduced in the cores of RF transformers?

• a) By using air cores.
• b) By using shell cores.
• c) By using laminated cores.
• d) By using ferrite cores.

© 2007− 2024 Eric Coates MA BSc. (Hons) All rights reserved. (Revision 15.00 29th December 2020)