Neets Module 2 Ch 5

Front 1

Q1. What is meant by "transformer action?"

Back 1

A1. The transfer of energy from one circuit to another circuit by electromagnetic induction.

Front 2

Q2. What are, the three basic parts of a transformer?

Back 2

A2. Primary winding; secondary winding; core.

Front 3

Q3. What are three materials commonly used as the core of a transformer?

Back 3

A3. Air; soft iron; steel.

Front 4

Q4. What are the two main types of cores used in transformers?

Back 4

A4. Hollow-core type; shell-core type.

Front 5

Q5. Which transformer windings are connected to an ac source voltage and to a load, respectively?

Back 5

A5. Primary to source; secondary to load.

Front 6

Q6. A transformer designed for high-voltage applications differs in construction in what way from a
transformer designed for low-voltage applications?

Back 6

A6. Additional insulation is provided between the layers of windings in the high-voltage transformer.

Front 7

Q8. What is meant by a "no-load condition" in a transformer circuit?

Back 7

A8. A voltage is applied to the primary, but no load is connected to the secondary.

Front 8

Q9. What is meant by "exciting current" in a transformer?

Back 8

A9. Exciting current is the current that flows in the primary of a transformer with the secondary
open (no load attached).

Front 9

Q10. What is the name of the emf generated in the primary that opposes the flow of current in the
primary?

Back 9

A10. Self-induced or counter emf.

Front 10

Q11. What causes a voltage to be developed across the secondary winding of a transformer?

Back 10

A11. The magnetic lines generated by the current in the primary cut the secondary windings and
induce a voltage into them.

Front 11

Q12. What is the phase relationship between the voltage induced in the secondary of an unlike-wound
transformer and the counter emf of the primary winding?

Back 11

A12. In phase. Remember, the cemf of the primary is 180 degrees out of phase with the applied
voltage. The induced voltage of the secondary of an unlike-wound transformer is also 180
degrees out of phase with the primary voltage.

Front 12

Q14. What is "leakage flux?"

Back 12

A14. Lines of flux generated by one winding which do not link the other winding.

Front 13

Q15. What effect does flux leakage in a transformer have on the coefficient of coupling (K) in the
transformer?

Back 13

A15. It causes K to be less than unity (1).

Front 14

Q23. Name the three power losses in a transformer.

Back 14

A23. Copper loss, eddy-current loss, and hysteresis loss.

Front 15

Q26. List five different types of transformers according to their applications.

Back 15

a. Power transformer
b. Autotransformer
c. Impedance-matching transformer
d. Audio-frequency transformer
e. Radio-frequency transformer

Front 16

Q28. What is the cause of most accidents?

Back 16

A28. Carelessness.

Front 17

Q29. Before working on electrical equipment containing capacitors, what should you do to the
capacitors?

Back 17

A29. Discharge them by shorting them to ground.

Front 18

Q30. When working on electrical equipment, why should you use only one hand?

Back 18

A30. To minimize the possibility of providing a path for current through your body.