11. 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 ________.
(a) 8 H
(b) 32 μH
(c) 64 μH
(d) 248 μH
12. 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
13. The following coils are in parallel: 75 μH, 40 μH, 25 μH, and 15 μH. The total inductance is approximately ________.
(a) 6.9 μH
(b) 14 μH
(c) 2.2 μH
(d) 155 μH
14. When the current through an inductor decreases, the amount of energy stored in the electromagnetic field ________.
(a) increases
(b) decreases
(c) remains the same
(d) doubles
15. The winding resistance of a coil can be increased by ________.
(a) increasing the number of turns
(b) using a thinner wire
(c) changing the core material
(d) increasing the number of turns or using thinner wire
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- 5555555555 22. 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 ________. (a) 87 mA (b) 870 mA (c) 87 A (d) 337 mA
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- 5555555555 10. 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