MCQOPTIONS
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MCQOPTIONS
This section includes 17 Mcqs, each offering curated multiple-choice questions to sharpen your Alternating Current and Voltage knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
What is the phase angle between the source voltage and current, when a 100 mH inductor with a reactance of 6 k , and a 1 k resistor are in series with a source? |
| A. | 0.1 degrees |
| B. | 9.0 degrees |
| C. | 61.0 degrees |
| D. | 81.0 degrees |
| Answer» E. | |
| 2. |
What is the phase angle of a 24 V ac parallel RL circuit when R = 45 ohms and X L = 1100 ohms? |
| A. | 0.001 degrees |
| B. | 2.300 degrees |
| C. | 87.600 degrees |
| D. | 89.900 degrees |
| Answer» C. 87.600 degrees | |
| 3. |
What is the impedance of a 1 kHz series RL circuit when R and X L are both 1000 ohms? |
| A. | 500 ohms |
| B. | 1000 ohms |
| C. | 1414 ohms |
| D. | 2000 ohms |
| Answer» D. 2000 ohms | |
| 4. |
What is the current rise after 2 time constants if V s = 12 V dc, R = 60 , and the inductor is rated at 24 mH? |
| A. | 79.9 mA |
| B. | 126.4 mA |
| C. | 173.0 mA |
| D. | 198.6 mA |
| Answer» D. 198.6 mA | |
| 5. |
Find I R and I L . |
| A. | I R = 50 mA, I L = 109 mA |
| B. | I R = 150 mA, I L = 9 mA |
| C. | I R = 50 mA, I L = 151 mA |
| D. | I R = 150 mA, I L = 53 mA |
| Answer» E. | |
| 6. |
With 100 V ac applied to the primary of a transformer so that it draws 500 mA, what will be the 300 V ac secondary current? |
| A. | 1500 mA |
| B. | 200 mA |
| C. | 167 mA |
| D. | 150 mA |
| Answer» D. 150 mA | |
| 7. |
If 360 V ac is the output of a 300-turn secondary winding, what is the input voltage when the primary winding has 150 turns? |
| A. | 2.4 V ac |
| B. | 150 V ac |
| C. | 180 V ac |
| D. | 720 V ac |
| Answer» D. 720 V ac | |
| 8. |
Find V R and V L . |
| A. | V R = 41.6 V, V L = 78.4 V |
| B. | V R = 48 V, V L = 110 V |
| C. | V R = 56 V, V L = 106 V |
| D. | V R = 60 V, V L = 60 V |
| Answer» D. V R = 60 V, V L = 60 V | |
| 9. |
What is the number of turns required in the secondary winding for a transformer when 120 volts is applied to a 2400-turn primary to produce 7.5 V ac at the secondary? |
| A. | 75 turns |
| B. | 150 turns |
| C. | 900 turns |
| D. | 1920 turns |
| Answer» C. 900 turns | |
| 10. |
An 18 V power supply is connected across a coil with a winding resistance of 180 . Current flow in the coil is |
| A. | 1 mA |
| B. | 10 mA |
| C. | 100 mA |
| D. | 1 A |
| Answer» D. 1 A | |
| 11. |
A 320 H coil is in series with a 3.3 k resistor. How long does it take for current to build up to its full value? |
| A. | 0.48 s |
| B. | 0.48 ms |
| C. | 0.48 s |
| D. | 48 s |
| Answer» E. | |
| 12. |
A switch, a 220 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? |
| A. | 91 mA |
| B. | 78 mA |
| C. | 57 mA |
| D. | 400 mA |
| Answer» C. 57 mA | |
| 13. |
The current through a 120 mH coil is changing at a rate of 150 mA/s. The voltage induced across the coil is |
| A. | 1.8 mV |
| B. | 18 mV |
| C. | 180 mV |
| D. | 1.25 mV |
| Answer» C. 180 mV | |
| 14. |
An inductor, a 1 k resistor, and a switch are connected in series across a 6 V battery. At the instant the switch is closed, the inductor voltage is |
| A. | 0 V |
| B. | 6 V |
| C. | 12 V |
| D. | 4 V |
| Answer» C. 12 V | |
| 15. |
Two inductors, L 1 and L 2 , are in parallel. L 1 has a value of 25 H and L 2 a value of 50 H. The parallel combination is in series with L 3 , a 20 H coil. The entire combination is across an ac source of 60 V r m s at 300 kHz. The total rms current is |
| A. | 87 mA |
| B. | 870 mA |
| C. | 87 A |
| D. | 337 mA |
| Answer» C. 87 A | |
| 16. |
An ohmmeter is connected across an inductor and the pointer indicates zero ohms. The inductor is |
| A. | good |
| B. | open |
| C. | shorted |
| D. | partly shorted |
| Answer» D. partly shorted | |
| 17. |
The voltage across a coil when di/dt = 20 mA/ s and L = 8 H is |
| A. | 16 mV |
| B. | 160 mV |
| C. | 1.6 mV |
| D. | 2.5 mV |
| Answer» C. 1.6 mV | |