A.C. Theory, Lvl 1: Lesson #1- Understanding inductance and How it affects a circuit Flashcards
The direction of induced ? flow through a conductor is determined by the direction of the magnetic field surrounding the conductor and the direction the conductor is traveling through the magnetic field.
Current
Whenever a conductor cuts through magnetic lines of flux, a ? is induced into the conductor.
Voltage
Whenever current flows through a conductor, a ? is created around the conductor.
Magnetic field
When no current flows in a conductor, free electrons move ? , and their magnetic fields cancel.
at random
When current flows in a conductor, a magnetic field is produced. As free electrons move in one direction, their individual magnetic fields ? .
add together
The important factors needed for generation of an induced voltage are a conductor, a magnetic field, and ? .
relative motion
As current flow decreases, the magnetic field surrounding the conductor will ? .
decreases
As the current passing through a coil increases, the magnetic field around the coil will ? .
increases
Whenever an electric current flows through a conductor, a magnetic field is formed ? the conductor.
around
? Law states that an induced voltage or current opposes the motion that causes the induced voltage or current.
Lenzs
Inductors always oppose a change of ? .
current
Counter Electromotive Force is sometimes called back EMF, and CEMF is ? out-of-phase with the applied voltage.
180°
CEMF ? the applied EMF when current is increasing and ? the applied EMF when current is decreasing.
subtracts from / adds to
List factors that work in combination to affect the inductance produced by an inductor.
-Cross sectional area of the core
-Permeability of the core material
-Spacing between the turns
The rate of current change in an inductive circuit can be described as a(n) ? curve.
exponential
How many time constants does it take for current to reach its maximum value in an inductive circuit?
5
At what percentage is the current after one time constant when the circuit is first energized?
63.2% of maximum
The unit of inductance is the ? , and inductance is represented by the letter ? .
henry / L
If a change of one ampere in one second causes one volt to be induced, you have ? of inductance.
one henry
In high frequency applications, ? inductors are used because of eddy current loss and hysteresis loss in the core material.
air core
In the formula for inductance, match the letter to what it represents.
Cross sectional area of the core = A
Length of the core used = I
Number of turns of wire = N
Permeability of the type of core material used = μ
Inductance will ? with an increase in the cross sectional area of the core.
Increase
Inductance is ? proportional to the length of the core used
inversely
Inductance will ? with an increase in the number of turns of wire.
increase
Inductance is ? proportional to the permeability of the type of core material used
directly
What is the formula for determining the time constant in an inductive circuit?
Given the formula for determining the counter EMF (induced voltage of a coil), drag the variables to the statement they represent.
