Electromagnetic Induction

Electromagnetic induction

voltage produced when lines of magnetic flux are cut by a conductor

Exponential curve

natural curve that is the rate at which current can rise or fall in an inductor

How many time constants are in the exponential curve

5 time constants

The exponential curve is divided into what units

time constants

Henry abbreviation

H

What is the basic unit of inductance

The Henry

Inductance is represented by what letter

L

Lenz’s law

law that explains relationship of movement, voltage polarity, and magnetic field polarity as they relate to magnetic induction

MOV stands for

metal oxide varistor

MOV

semiconductor device that changes its resistance in accord with voltage applied across it

R-L time cosntant

formula to determine rate of rise or fall of current in an inductive circuit

Voltage spike

momentary increase of voltage lasting 2 ns or less

When do voltage spikes usually occur in a circuit

When the circuit opens

Weber (Wb)

measure of magnetic lines of flux

1 Wb equals

100 million lines of flux

What is created when a conductor is moved through a magnetic field

a voltage is induced in the conductor

What determines induced voltage polarity

direction of relative motion

polarity of the magnet

For electron current flow left hand or right hand is used

left hand

Important factors in electromagnetic induction

conductor

magnetic field

relative motion

What 3 factors affect the amount of induced voltage

number of turns of wire

strength of the magnetic field

speed of cutting action

What happens to induced voltage if the relative motion, number of turns of wire, speed, or strength of magnetic field increases

induced voltage increases

Lenz’s law states that an induced voltage will

oppose the motion that causes it

Induced voltage is _ to rate of change of current

proportional

At what point of the exponential curve will an inductor reach its full value

it won’t, it will get close and at that point it will be considered to be complete

What determines amount of inductance

physical properties and construction of the coil

Inductance formula

L = 4piN2muA/l

R-L time constant formula

T = L/R

Induced voltage spike formula

EMF = - L (delta i/delta t)

DIodes can only be used in what circuits

DC

What determines magnetic polarity when current flows through a conductor

direction of current flow

What determines strength of magnetic field when current flows through a conductor

amount of current