# QUIZ OF DAY-TRANSFORMER BASIC NUMERICAL QUESTIONS AND ANSWERS

## QUIZ OF DAY-TRANSFORMER BASIC

Category –EE Online Test

Attempt Free QUIZ OF DAY-TRANSFORMER BASIC Here. Read The Important Electrical MCQ From Below.

1. What kVA rating is required for a transformer that must handle a maximum load current of 8 A with a secondary
voltage of 2 kV?
A. 4 kVA
B. 0.25 kVA
C. 16 kVA
D. 8 kVA

2. The turns ratio required to match an 80 ohm source to a 320 ohm load is
A. 80
B. 20
C. 4
D. 2

3. When the turns ratio of a transformer is 20 and the primary ac voltage is 12 V, the secondary voltage is
A.12 V
B.120 V
C.240 V
D.2,400 V

QUIZ OF DAY-TRANSFORMER BASIC

4. If a transformer has 50 turns in the primary winding and 10 turns in the secondary winding, what is the reflective resistance if the secondary load resistance is 250 ohm?
A. 250 ohm
B.25 ohm
C.6,250 ohm
D. 62,500 ohm

5. A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary winding. The
turns ratio is
A.0.2
B.0.4
C.5
D.25

6. The primary winding of transformer has 110 V ac across it. What is the secondary voltage if the turns ratio is 8?
A.8.8 V
B.88 V
C.880 V
D. 8,800 V

7. To step 110 V ac down to 20 V ac, the turns ratio must be
A.5.5
B.18
C.0.18
D. 0.018

QUIZ OF DAY-TRANSFORMER BASIC

8. The mutual inductance when k = 0.65, L1 = 2 micro H, and L2 = 5 micro H is
A. 2 micro H
B. 2 micro H
C. 4 micro H
D. 8 micro H

9. If 25 W of power are applied to the primary of an ideal transformer with a turns ratio of 10, the power
delivered to the secondary load is
A.25 W
B.0 W
C.250 W
D.2.5 W

10. A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance, RL, is 120 ohm. What is the approximate voltage across the load?
A.7.3 V
B.73 V
C.88 V
D.880 V

11. How many primary volts must be applied to a transformer with a turns ratio of 0.1 to obtain a secondary voltage of 9 V?
A.9 V
B.90 V
C.900 V
D.0.9 V

QUIZ OF DAY-TRANSFORMER BASIC

12. In a certain loaded transformer, the secondary voltage is one-fourth the primary voltage. The secondary current is
A. one-fourth the primary current
B.four times the primary current
C.equal to the primary current
D.one-fourth the primary current and equal to the primary current

13. A certain transformer has a turns ratio of 1 and a 0.85 coefficient of coupling. When 2 V ac is applied to the
primary, the secondary voltage is
A.1.7 V
B.0.85 V
C.1 V
D.0 V

14.The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 ohm  load. The turns ratio is 3:1. What is the secondary voltage?
A.2 V
B.20 V
C.180 V
D.18 V

QUIZ OF DAY-TRANSFORMER BASIC

15. The primary winding of a power transformer should always be
A. open
B. shorted
C. switched
D. fused

16. A certain amplifier has 600 ohm internal resistance looking from its output. In order to provide maximum power to a 4 ohm speaker, what turns ratio must be used in the coupling transformer?
A. 8
B.0.8
C.0.08
D. 80

17.A transformer
A. changes ac to dc
B. changes dc to ac
C. steps up or down dc voltages
D. steps up or down ac voltages

QUIZ OF DAY-TRANSFORMER BASIC

18. The primary of a transformer is connected to a 6 V battery. The turns ratio is 1:3 and the secondary load, RL,
is 100 ohm. The voltage across the load is
A.0 V
B.6 V
C.18 V
D.2 V

19.To step 120 V ac up to 900 V ac, the turns ratio must be
A.75
B.750
C.7.5
D.0.13

QUIZ OF DAY-TRANSFORMER BASIC

20. When a 200 ohm load resistor is connected across the secondary winding of a transformer with a turns ratio of 4, the source “sees” a reflective load of
A.50 ohm
B.12.5 ohm
C.800 ohm
D.0 ohm

21. In a certain transformer, the input power to the primary is 120 W. If 8.5 W are lost to the winding resistance, what is the output power to the load, neglecting any other issues?
A.0 W
B.14.1 W
C.111.5 W
D.1,020 W

QUIZ OF DAY-TRANSFORMER BASIC

22. When a 6 V battery is connected across the primary of a transformer with a turns ratio of 8, the secondary
voltage is
A.0 V
B.6 V
C.48 V
D.0.75 V

23.What is the coefficient of coupling for a transformer in which 4% of the total flux generated in the primary does not pass through the secondary?
A.0.4
B.4
C.9.6
D.0.96

24. A transformer has a 1:6 turns ratio and a secondary coil load resistance of 470 ohm. The load resistance as seen by the source is
A.1.3 ohm
B.7.8 ohm
C.78 ohm
D. 13 ohm

QUIZ OF DAY-TRANSFORMER BASIC