TRANSFORMER
1.The primary winding of a 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
2.To step 110 V ac down to 20 V ac, the turns ratio must be
A. 5.5B. 18
C. 0.18D.0.018
3.The mutual inductance when k = 0.65, L1 = 2 H, and L2 = 5 H is
A. 2 mH
B. 2 H
C. 4 H
D. 8 H
4.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
5.A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance, RL, is 120 . What is the approximate voltage across the load?
A. 7.3 VC. 88
B. 73 VD. 880 V
6. 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
7. 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
8. 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
9. The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 load. The turns ratio is 3:1. What is the secondary voltage?
A. 2 V
B. 20 V
C. 180 V
D. 18 V
10. The primary winding of a power transformer should always be
A. openB. shortedC. switchedD. fused
11.A certain amplifier has 600 internal resistance looking from its output. In order to provide maximum power to a 4 speaker, what turns ratio must be used in the coupling transformer?
A. 8B. 0.8
C. 0.08D.80
12. 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 . The voltage across the load is
A. 0 V
B. 6 V
C. 18 V
D. 2 V
13. To step 120 V ac up to 900 V ac, the turns ratio must be
A. 75B. 750
C. 7.5D.0.13
14. When a 200 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
B. 12.5
C. 800
D. 0
15.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
16. 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
17. 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. 0.4B. 4
C. 9.6D.0.96
18. A transformer has a 1:6 turns ratio and a secondary coil load resistance of 470 . The load resistance as seen by the source is
A. 1.3
B. 7.8
C. 78
D. 13
19.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
20.The turns ratio required to match an 80 source to a 320 load is
A. 80B. 20
C. 4D.2
21.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
22.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 ?
A. 250
B. 25
C. 6,250
D. 62,500
23.A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary winding. The turns ratio is
A. 0.2B. 0.4C. 5D. 25