Inductors

Inductance

Property in an electrical circuit that resists a change in current

Inductor

An electronic component that is used to produce inductance in a circuit by storing energy in a magnetic field In DC

Len’s law

A principle that states the direction of induced current in a circuit opposes the change in magnetic flux that produced it.

henry (L)

Unit for inductance, representing the amount of inductance in a circuit where a change in current induces one volt of electromotive force per ampere per second.

Stronger magnetic field produces

higher induced voltage according to Faraday's law of electromagnetic induction.

Toroid inductor

A type of inductor shaped like a doughnut, consisting of a coil of wire wound around a circular core, which helps confine the magnetic field and improve inductance.

Current going through an inductor produces

An expanding or collapsing magnetic field cutting across the wires of the coil which induces a CEMF (counter electromotive force) that opposes the change in current.

Transient response

The response of the current and voltage in the circuit after an instant change in applied voltage or current is characterized by a temporary period of adjustment before reaching a steady state.

Opposition to the rise and decay of current occurs

When there is a change in applied voltage across the inductor, causing a counteracting electromotive force.

RL circuit

A circuit that contains resistance and inductor

RL time constant (t)

The amount of time to complete the transient response depends upon the values of R and L in the circuit

mutual inductance

When two coils are within magnetic reach of each other so that the flux lines of one coil link with, or cut across, the other coil

Coupling

The degree to which the lines of the force of one coil link with the windings of the second coil

Unity coupling

All lines of one coil link with the other coil, resulting in maximum mutual inductance.

Reactance (X)

Opposition to an alternating current due inductance or capacitance

Inductive reactance (XL)

When reactance is caused by an inductor and measured in Ohms

CEMF is ___ degrees out of phase with the source voltage

180

what two things increase inductive reactance

Increasing frequency and inductance

True power

The actual power used by a circuit measured in watts

Reactive power

The power used to build the magnetic field is returned to the source when the field collapses and measured in volt-amperes reactive (VAR).

Apparent power

The combination of true power and reactive power gives rise to a measure of power that appears to be delivered to a load and measured in volt-amperes (VA)

Power factor

The ratio of true power to apparent in an AC circuit or Resistance/impedance (R/Z)

In DC the power factor is

1

inductors causes a delay for current by

0- 90 degrees in phase

current is drastically reduced by

Impedance in an AC circuit due to the presence of inductors.

Resistance and reactance are

90 degrees out of phase with each other.

Impedance (Z)

the total opposition to current flow in an AC circuit, combining resistance and reactance.

Phase angle (Θ)

It represents the phase displacement between the voltage and current in an AC circuit resulting from the reactive component.

Does an Ohm meter read inductive reactance or impedance?

An Ohm meter reads resistance, not reactance or impedance. Inductive reactance can only be measured in an AC circuit with a frequency applied.

Series rules

LT= L1+L2+L3+…

XLT=XL1=XL2+XL3+….

Parallel rules

XLT=1/(1/XL1+1/XL2+….) the reciprocal

LT=1/(1/L1+1/L2+1/L3…) the reciprocal

3 values that stay constant in (LRT chart)

LΩ=+90

RΩ=0

VT=0

Formula for XL

XL=2πfL, where f is the frequency and L is the inductance.

Formula for inductance (L)

L=XL/(2πf), where XL is the inductive reactance and f is the frequency.

time constant for inductor

L/R= T where L is inductance and R is resistance.

The skin affect is most pronounced when

The frequency is high

The high voltage spike produced when the current through a coil is cut off is known as ___________________.

inductive kick

What affects the magnitude of an inductor?

-Size and shape of the coil

-Number of turns

-type of core material

A coil of wire will produce a phase shift
caused by _____.

(self)induction