Here is the "Electricity - Basic Navy Training Courses"
(NAVPERS 10622) in its entirety. It should provide one of the Internet's
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Contents. • U.S. Government Printing Office; 1945 - 618779
Test your comprehension of transformer principles with this 10 question quiz.
Chapter 20 Quiz - Transformers
1. How is energy transferred from the primary
to the secondary of a transformer?
2. Suppose d.c. were fed into the primary of a transformer, what would happen?
3. Explain how the secondary current controls the amount of primary current?
4. A welding transformer has a one-turn secondary that delivers 400 amperes.
The primary has 800 turns. What is the primary current?
5. You want to build a transformer to step-down 440 volts to 110 volts. If 2,080
turns are used on the secondary, how many turns will be used on the primary?
6. A loaded secondary draws 80 amperes at 220 volts. If the primary is 600 volts,
what is the primary current?
7. A 440/110 volt transformer is designed for 1/4 volt per turn. How many turns
on primary and secondary?
8. Is it absolutely correct to say that transformers ate 100 percent efficient?
9. Two losses occur in a transformer? What are they?
10. How can the losses of a transformer be reduced?
to Chapter 20
Chapter 20 Answers
1. The magnetic flux field set up by the primary current
carries the primary's energy to the secondary.
2. D.C. produces no continuous voltage of self induction,
therefore a very high current would flow. The primary would burn out.
3. The secondary's flux field cancels the primary's. This
reduces the Esi in the primary and adjusts primary current in exact proportions
to the secondary current.
4. 1/2 ampere.
5. 8320 turns.
6. 29-1/3 amps.
7. 1,760 and 440 turns.
9. Iron losses - hysteresis and eddy currents. Copper losses
10. Iron, by using soft iron or silica steel in laminated
form. Copper; by shortening the length per turn, and using heavy wire. Both,
by cooling entire assembly.