1. What type of core is used for a high frequency transformer?
a) open iron core
b) air core
c) closed iron core
d) none of these
ans. b
2. Which of the statements given below is true for the auto transformer?
a) It has to separate windings connected in series externally
b) it has only one winding
c) it can only step down the voltage
d) it is most suitable for power transformation
ans.b
3. The self induced voltage of a coil depends upon
a) the voltage applied to the coil
b) the shape of the iron core
c) the shape of the bobbin
d) the number of turns of the coil
ans. d
4. Which of the following is a correct statement about eddy currents?
a) Eddy currents improve the efficiency of a motor
b) Eddy currents heat up the copper winding
c) Eddy currents heat up the metal parts
d) Eddy currents are used for arc welding.
ans. c
5. The use of higher flux density in transformer design
a) increases the weight per kVA
b) decreases the weight per kVA
c) increases the weight per kW
d) decreases the weight per kW
ans. b
6. The transformer oil used in transformers provides
a) insulation and cooling
b) cooling and lubrication
c) insulation and lubrication
d) insulation ,cooling and lubrication
ans. a
7. The induced emf in the secondary of a transformer will depend on
a) frequency of the supply only
b) number of turns in secondary only
c) maximum flux in the core only
d) frequency , flux and number of turns in the secondary .
ans. d
8. A transformer has a turns ratio of 1 to 10 and a resistance of 5000 ohms is connected across the secondary terminals, the resistance offered to a current flowing in the primary will be
a) 50 ohms
b) 500 ohms
c) 5000 ohms
d) 50 kilo ohms
ans. a
9. Two transformers are operating in parallel, they will share the load depending upon their
a) efficiency
b) ratings
c) leakage reactance
d) per-unit impedance
ans. d
10. Which of the following statements about a short-circuit power transformer is true?
a) There is a fuse in its primary circuit
b) There is a bimetallic switch in its primary circuit
c) There is a fast magnetic switch in its primary circuit
d) The short-circuit current can continuously flow through it without causing a damage
ans. d
a) open iron core
b) air core
c) closed iron core
d) none of these
ans. b
2. Which of the statements given below is true for the auto transformer?
a) It has to separate windings connected in series externally
b) it has only one winding
c) it can only step down the voltage
d) it is most suitable for power transformation
ans.b
3. The self induced voltage of a coil depends upon
a) the voltage applied to the coil
b) the shape of the iron core
c) the shape of the bobbin
d) the number of turns of the coil
ans. d
4. Which of the following is a correct statement about eddy currents?
a) Eddy currents improve the efficiency of a motor
b) Eddy currents heat up the copper winding
c) Eddy currents heat up the metal parts
d) Eddy currents are used for arc welding.
ans. c
5. The use of higher flux density in transformer design
a) increases the weight per kVA
b) decreases the weight per kVA
c) increases the weight per kW
d) decreases the weight per kW
ans. b
6. The transformer oil used in transformers provides
a) insulation and cooling
b) cooling and lubrication
c) insulation and lubrication
d) insulation ,cooling and lubrication
ans. a
7. The induced emf in the secondary of a transformer will depend on
a) frequency of the supply only
b) number of turns in secondary only
c) maximum flux in the core only
d) frequency , flux and number of turns in the secondary .
ans. d
8. A transformer has a turns ratio of 1 to 10 and a resistance of 5000 ohms is connected across the secondary terminals, the resistance offered to a current flowing in the primary will be
a) 50 ohms
b) 500 ohms
c) 5000 ohms
d) 50 kilo ohms
ans. a
9. Two transformers are operating in parallel, they will share the load depending upon their
a) efficiency
b) ratings
c) leakage reactance
d) per-unit impedance
ans. d
10. Which of the following statements about a short-circuit power transformer is true?
a) There is a fuse in its primary circuit
b) There is a bimetallic switch in its primary circuit
c) There is a fast magnetic switch in its primary circuit
d) The short-circuit current can continuously flow through it without causing a damage
ans. d
