Discussion
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- Question
The following coils are in parallel: 75 µH, 40 µH, 25 µH, and 15 µH. The total inductance is approximately
Options- A. 6.9 µH
- B. 14 µH
- C. 2.2 µH
- D. 155 µH
- Correct Answer
- 6.9 µH
- 1. Three 15 mH inductors are in series. The total inductance is
Options- A. 15 mH
- B. 30 mH
- C. 45 mH
- D. 5 mH Discuss
- 2. Two inductors, L1 and L2, are in parallel. L1 has a value of 25 µH and L2 a value of 50 µH. The parallel combination is in series with L3, a 20 µH coil. The entire combination is across an ac source of 60 Vrms at 300 kHz. The total rms current is
Options- A. 87 mA
- B. 870 mA
- C. 87 A
- D. 337 mA Discuss
- 3. The inductance of an iron-core coil decreases if
Options- A. the number of turns is decreased
- B. the iron core is removed
- C. the length of the coil decreases
- D. none of the above Discuss
- 4. Two 10 H inductors are in parallel and the parallel combination is in series with a third 10 H inductor. What is the approximate total reactance when a voltage with a frequency of 7 kHz is applied across the circuit terminals?
Options- A. 219 kΩ
- B. 66 kΩ
- C. 660 kΩ
- D. 1.3 MΩ Discuss
- 5. A 320 µH coil is in series with a 3.3 kΩ resistor. How long does it take for current to build up to its full value?
Options- A. 0.48 s
- B. 0.48 ms
- C. 0.48 µs
- D. 48 s Discuss
- 6. A switch, a 220 Ω resistor, and a 60 mH inductor are in series across a 20 V battery. What is the current through the inductor two time constants after the switch is closed?
Options- A. 91 mA
- B. 78 mA
- C. 57 mA
- D. 400 mA Discuss
- 7. An 18 V power supply is connected across a coil with a winding resistance of 180 Ω. Current flow in the coil is
Options- A. 1 mA
- B. 10 mA
- C. 100 mA
- D. 1 A Discuss
- 8. A 5 mH, a 4.3 mH, and a 0.6 mH inductor are connected in parallel. The total inductance is
Options- A. 9.9 mH
- B. greater than 5 mH
- C. 9.9 mH or greater than 5 mH
- D. less than 0.6 mH Discuss
- 9. When the current through an inductor decreases, the amount of energy stored in the electromagnetic field
Options- A. increases
- B. decreases
- C. remains the same
- D. doubles Discuss
- 10. An inductor, a 1 kΩ resistor, and a switch are connected in series across a 6 V battery. At the instant the switch is closed, the inductor voltage is
Options- A. 0 V
- B. 6 V
- C. 12 V
- D. 4 V Discuss
Inductors problems
Search Results
Correct Answer: 45 mH
Correct Answer: 870 mA
Correct Answer: the number of turns is decreased
Correct Answer: 660 kΩ
Correct Answer: 0.48 µs
Correct Answer: 78 mA
Correct Answer: 100 mA
Correct Answer: less than 0.6 mH
Correct Answer: decreases
Correct Answer: 6 V
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