1. A sine wave voltage is applied across an inductor. When the frequency of the voltage is decreased, the current
2. 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?
3. An ohmmeter is connected across an inductor and the pointer indicates zero ohms. The inductor is
4. Two inductors, L1 and L2, are in parallel. L1 has a value of 25 H and L2 a value of 50 H. The parallel combination is in series with L3, a 20 H coil. The entire combination is across an ac source of 60 Vrms at 300 kHz. The total rms current is
5. 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
6. The winding resistance of a coil can be increased by
7. An inductance of 0.43 mH is smaller than
8. An inductor and a resistor are in series with a sine wave voltage source. The frequency is set so that the inductive reactance is equal to the resistance. If the frequency is increased, then
9. The current through a 120 mH coil is changing at a rate of 150 mA/s. The voltage induced across the coil is
10. When the current through an inductor decreases, the amount of energy stored in the electromagnetic field
11. Three 15 mH inductors are in series. The total inductance is
12. An 18 V power supply is connected across a coil with a winding resistance of 180 . Current flow in the coil is
13. 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?
14. 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?
15. Five inductors are connected in series. The lowest value is 8 μH. If the value of each inductor is twice that of the preceding one, and if the inductors are connected in order of ascending values, the total inductance is
16. The inductance of an iron-core coil decreases if
17. The following coils are in parallel: 75 H, 40 H, 25 H, and 15 H. The total inductance is approximately
18. When the current through an inductor is cut in half, the amount of energy stored in the electromagnetic field
19. The permeability of a core material is an indication of the ability of the material to establish a magnetic field.
20. XL is directly proportional to frequency and inductance.
21. An induced voltage is produced as a result of a dc voltage.
22. Faraday's law states that relative motion between a magnetic field and a coil induces a voltage across the coil.
23. Inductance is the property of an inductor that produces an opposition to any change in current.
24. All coil cores are made of iron.
25. Inductance is indirectly proportional to the square of the number of turns, the permeability, and the cross-sectional area of the core.