THIRD-CLASS ENGINEER – SET OF SPECIMEN EXAMINATION QUESTIONS ELECTROTECHNOLOGY QUESTION PAPER

ELECTROTECHNOLOGY

Time allowed: 3.5 hours

Six (6) questions only to be attempted

(1) What is a Wattmeter? Describe, with the aid of a sketch, the internal construction of a Wattmeter.

(2) State the advantages of the alternating current generators over the direct current generators.

(3) Describe, with the aid of a sketch, the essential parts of a typical gas engine ignition system.

(4) A wire is cutting magnetic lines of force at the rate of 200,000,000 lines per second.

What average voltage is induced across the terminals of the wire?

(5) Describe the construction of lead storage cell. Give the chemical reaction produced in the

cell on discharge.

(6) A cell whose internal resistance is 0.16 ohm is delivering 0.5 amps. The external resistance

is 2.8 ohms. Find:

(a) The number of Volts used in overcoming the internal resistance;

(b) The terminal voltage;

(c) The Electromotive Force.

(7) Explain the effects of temperature on resistance of the following conductors:

(a) Aluminum;

(b) Manganin;

(c) Liquid;

(d) Carbon.

(8) A wire has a resistance of 10 ohms at 0 °C and 15 ohms at 100 °C. What is the

temperature coefficient of the resistance of the material? At what temperature will its

resistance be 30 ohms?

(9) The brush potential of a generator is 110 volts. The total line resistance is 6 ohms.

How much extra line resistance is necessary to limit the current flow to 10 amperes

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M❤K