Transformers problems
- 1. A transformer
Options- A. changes ac to dc
- B. changes dc to ac
- C. steps up or down dc voltages
- D. steps up or down ac voltages Discuss
Correct Answer: steps up or down ac voltages
- 2. The primary winding of a power transformer should always be
Options- A. open
- B. shorted
- C. switched
- D. fused Discuss
Correct Answer: fused
- 3. The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 Ω load. The turns ratio is 3:1. What is the secondary voltage?
Options- A. 2 V
- B. 20 V
- C. 180 V
- D. 18 V Discuss
Correct Answer: 20 V
- 4. 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?
Options- A. 9 V
- B. 90 V
- C. 900 V
- D. 0.9 V Discuss
Correct Answer: 90 V
Explanation:
We know that, V2/V1 = N2/N1.
Given V2 = 9v, N2/N1 = 0.1
Therefore, 9v/V1 = 0.1
V1 = 9v/0.1 = 90v.
Given V2 = 9v, N2/N1 = 0.1
Therefore, 9v/V1 = 0.1
V1 = 9v/0.1 = 90v.
For more detail: Step Down Transformer - Circuit with Simulation.
- 5. A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary winding. The turns ratio is
Options- A. 0.2
- B. 0.4
- C. 5
- D. 25 Discuss
Correct Answer: 5
- 6. 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
Options- A. 1.7 V
- B. 0.85 V
- C. 1 V
- D. 0 V Discuss
Correct Answer: 1.7 V
- 7. 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 Ω. The voltage across the load is
Options- A. 0 V
- B. 6 V
- C. 18 V
- D. 2 V Discuss
Correct Answer: 0 V
- 8. 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?
Options- A. 0 W
- B. 14.1 W
- C. 111.5 W
- D. 1,020 W Discuss
Correct Answer: 111.5 W
- 9. A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance, RL, is 120 Ω. What is the approximate voltage across the load?
Options- A. 7.3 V
- B. 73 V
- C. 88 V
- D. 880 V Discuss
Correct Answer: 7.3 V
- 10. 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
Options- A. 25 W
- B. 0 W
- C. 250 W
- D. 2.5 W Discuss
Correct Answer: 25 W
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