Discussion
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- Question
To step 110 V ac down to 20 V ac, the turns ratio must be
Options- A. 5.5
- B. 18
- C. 0.18
- D. 0.018
- Correct Answer
- 0.18
ExplanationVp/Vs = Np/Ns
Vs = (Ns/Np)Vp
We required turns ratio i.e., (Ns/Np)
= Vs/Vp
= 20/110
= 0.181818182
[Note: p - primary; s - secondary]
For step down transfer, the turns ratio will be less than 1.
For simulation: Step-Down Transformer Circuit Simulator.
Transformers problems
Search Results
- 1. In a certain loaded transformer, the secondary voltage is one-fourth the primary voltage. The secondary current is
Options- 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 Discuss
Correct Answer: four times the primary current
- 2. A capacitor of 2,000 pF is greater than
Options- A. 0.02 µF
- B. 0.002 µF
- C. 0.0002 µF
- D. 0.0000002 F Discuss
Correct Answer: 0.0002 µF
- 3. A 330 pF capacitor and a 220 pF capacitor are each connected across a 6 V dc source. The voltage across the 330 pF capacitor is
Options- A. 3 V
- B. 6 V
- C. 4 V
- D. 0 V Discuss
Correct Answer: 6 V
- 4. A capacitor of 0.02 µF is larger than
Options- A. 0.000020 F
- B. 200,000 pF
- C. 2,000 pF
- D. all of the above Discuss
Correct Answer: 2,000 pF
- 5. A 0.47 µF capacitor is across a 2 kHz sine wave signal source. The capacitive reactance is
Options- A. 170 Ω
- B. 17 Ω
- C. 0.000169 Ω
- D. 1.7 Ω Discuss
Correct Answer: 170 Ω
- 6. When a 200 Ω load resistor is connected across the secondary winding of a transformer with a turns ratio of 4, the source "sees" a reflective load of
Options- A. 50 Ω
- B. 12.5 Ω
- C. 800 Ω
- D. 0 Ω Discuss
Correct Answer: 12.5 Ω
- 7. 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?
Options- A. 4 kVA
- B. 0.25 kVA
- C. 16 kVA
- D. 8 kVA Discuss
Correct Answer: 16 kVA
- 8. The primary winding of a transformer has 110 V ac across it. What is the secondary voltage if the turns ratio is 8?
Options- A. 8.8 V
- B. 88 V
- C. 880 V
- D. 8,800 V Discuss
Correct Answer: 880 V
Explanation:
V2/V1 = N2/N1
Turns ratio = N2/N1 = 8.
V2/110 = 8
V2 = 8 x 110
V2 = 880v.- 9. 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 Ω?
Options- A. 250 Ω
- B. 25 Ω
- C. 6,250 Ω
- D. 62,500 Ω Discuss
Correct Answer: 6,250 Ω
- 10. To step 120 V ac up to 900 V ac, the turns ratio must be
Options- A. 75
- B. 750
- C. 7.5
- D. 0.13 Discuss
Correct Answer: 7.5
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