3.11 Inductance And Inductors Flashcards
What is electromagnetic induction?
Electromotive force can be produced across a conductor in a magnetic field
How can an electromotive force be induced across a conductor?
-by movement of a permanent magnet and the conductor
-by changing the strength of the magnetic field passing through the conductor
What is faradays law?
A voltage is induced across a conductor whenever relative motion exists between the conductor and a magnetic field
If a conductor is moved through a magnetic field what is produced?
An electromotive force is induced across the conductor
What direction must a conductor travel to gain an electromotive force when going through induction?
In a direction that cuts through the lines
What is electromagnetic induction also known as?
Generator principle
Why is electromagnetic induction also referred to as the generator principle?
Because its the principle of operation of electrical generators
The direction of the induced voltage depends on?
-direction in which the conductor is moved
-direction of the magnetic field
What happens if the movement of the magnetic field through a coil gets faster?
The induced voltage increases
What three factors determine the magnitude of voltage in an induction coil?
-number of turns
-the relative speeds of coil and magnet
-the strength of the magnetic field
When a magnet is passed back and forth between a conductive coil is it negative or positive?
Both (negative one direction and positive in the other)
What is mutual inductance?
When a change in current in one coil causes and induced electromotive force in another coil placed near the first coil
What is the most common application of mutual induction?
In transformers
In mutual inductance if the primary coil receives a current, what happens to the secondary coil?
The change in magnetic field causes a voltage to be induced
What physical factors will increase the mutual inductance of a pair of coils?
-increasing the number of turns on the coils
-increasing cross-sectional area of the coils
-decreasing the length of coils
-increasing the permeability of the material used in the core
What does lenz’s law state?
The current caused by an individual voltage always opposes the cause of the induction
When should you use Flemings LH rule?
When you have a current flowing through a magnetic field and want to figure out the force direction
When should you use Flemings right hand rule?
When you are moving a conductor through a magnetic field and want to find out which way the current goes
When the current through a coil increases, what happens to the magnetic field?
It also increases
Self-inductance has the symbol of?
L
What are the units of self-inductance?
Henry (H)
Why does disconnecting coils require special caution?
The rate of change in current is extremely high
What is placed in parallel when disconnecting a coil?
A freewheeling diode
Can you saturate an inductor if it doesn’t have a core?
No
When an object is fully saturated what happens if additional energy is supplied?
It gets wasted as heat
What is the job of a transformer?
To allow AC voltages to be changed in different parts of a circuit or system without significant loss of energy
Why is an inductor sometimes referred to as a choke?
It can be used to block AC currents but allow DC currents to flow
How many phases can a current transformer come in?
-single
-two
-three
What are current transformers?
They’re transformers that measure current
