Q.1

The inductance of an iron-core coil decreases if

  • the number of turns is decreased
  • the iron core is removed
  • the length of the coil decreases
  • none of the above
Q.2

The winding resistance of a coil can be increased by

  • increasing the number of turns
  • using a thinner wire
  • changing the core material
  • increasing the number of turns or using thinner wire
Q.3

When the current through an inductor is cut in half, the amount of energy stored in the electromagnetic field

  • is quartered
  • quadruples
  • doubles
  • does not change
Q.4

ThreemH inductors are in series. The total inductance is

  • 15 mH
  • 30 mH
  • 45 mH
  • 5 mH
Q.5

A sine wave voltage is applied across an inductor. When the frequency of the voltage is decreased, the current

  • is increased
  • is decreased
  • does not change
  • momentarily goes to zero
Q.6

All coil cores are made of iron.

  • True
  • False
Q.7

The permeability of a core material is an indication of the ability of the material to establish a magnetic field.

  • True
  • False
Q.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

  • VR ≥ VL
  • VL < VR
  • VL = VR
  • VL > VR
Q.9

When the current through an inductor is cut in half, the amount of energy stored in the electromagnetic field

  • is quartered
  • quadruples
  • doubles
  • does not change
Q.10

An ohmmeter is connected across an inductor and the pointer indicates zero ohms. The inductor is

  • good
  • open
  • shorted
  • partly shorted
Q.11

A 2 mH, a 3.3 mH, and a 0.2 mH inductor are connected in series. The total inductance is

  • 55 mH
  • less than 0.2 mH
  • less than 5.5 mH
  • 5.5 mH
Q.12

Inductance is indirectly proportional to the square of the number of turns, the permeability, and the cross-sectional area of the core.

  • True
  • False
Q.13

Inductors add in parallel.

  • True
  • False
Q.14

XL is directly proportional to frequency and inductance.

  • True
  • False
Q.15

The current through amH coil is changing at a rate ofmA/s. The voltage induced across the coil is

  • 1.8 mV
  • 18 mV
  • 180 mV
  • 1.25 mV
Q.16

When the current through an inductor decreases, the amount of energy stored in the electromagnetic field

  • increases
  • decreases
  • remains the same
  • doubles
Q.17

A 2 mH, a 3.3 mH, and a 0.2 mH inductor are connected in series. The total inductance is

  • 55 mH
  • less than 0.2 mH
  • less than 5.5 mH
  • 5.5 mH
Q.18

When the current through an inductor decreases, the amount of energy stored in the electromagnetic field

  • increases
  • decreases
  • remains the same
  • doubles
Q.19

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

  • 8 H
  • 32 μH
  • 64 μH
  • 248 μH
Q.20

A 5 mH, a 4.3 mH, and a 0.6 mH inductor are connected in parallel. The total inductance is

  • 9.9 mH
  • greater than 5 mH
  • 9.9 mH or greater than 5 mH
  • less than 0.6 mH
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