INDUCTANCE & INDUCTIVE REACTANCE (030201d) Flashcards
How does the counter EMF produced by the changing magnetic field interact with the original circuit characteristics?
It will tend to aid the original current
When the armature of an AC operated relay pulls in, then the inductance of the operating coil would ______
Increase
If a small core within a coil is replaced with a bigger core, the inductance of the coil would _____
Decrease
What is the symbol used to represent inductance?
L
Which law states that any induced current will produce a flux that will oppose any change in the original flux
Lenz’s law
When using the left-hand rule to determine the polarity of the counter EMF in a coil, the thumb points in the direction of the ______ ______
Relative motion
The process by which a voltage is produced by the interaction between a magnetic field, and a conductor is known as _______
Induction
If the rate of change of current in a coil increases, then the magnitude of the induced EMF will ______
Increase
How many time constants are needed to reach a steady value of current?
5
True or false
Whenever a resistor is connected in parallel with a DC operated coil, the purpose of this resistor is to reduce the high induced voltage due to the collapsing magnetic field
True
What percentage of the final current is one time constant?
63.2%
If the core of an iron core coil is removed, then the inductive reactance of the coil would _____
Decrease
Inductive reactants varies directly with _____
Frequency
In a purely inductive AC circuit, the current will always _____ the voltage drop due to inductive reactance by 90°
Lag
What is the phase relationship between applied voltage and current in a purely inductive AC circuit?
90°
True or false
In an AC circuit containing a pure inductor, current will always lead voltage by 90°
False!!!
Current LAGS voltage in a purely inductive circuit
What does the symbol Q represent?
Reactive power
What is the unit of measurement for reactive power?
VARs
Volt-ampere reactive
Decreasing the resistance of the wire used in a coil will ________ the phase angle
Increase
If a certain size core is replaced with a smaller core, what happens to the inductance of the coil?
It decreases
What symbol is used to represent the unit of measurement for inductance?
H
Why is a resistor connected in parallel with a DC operated coil?
To reduce the high induced voltage due to the collapsing magnetic field
If the core of an iron core coil is removed, then the inductive reactance of the coil would ______
Decrease
When the armature of an AC operated relay pulls in, the inductive reactance of the coil will ______
Increase
