Applying Electromagnetism/Transformers

Electric Circuit

unbroken path along which an electric current exists or flow

What is the symbol for electric current (electricity)

I

How is electric current (electricity) measured

ampere (A)

What is electric current

flow or movement of electrons 

There is electricity ONLY when electrons move in _ direction

One

What is the path of current flow

from negative to positive outside a conductor

What conditions are needed for current to flow

• conductive path

• a difference in potential

• resistance

What is a conductive path

material that readily conducts electric current

What is potential difference

measure of amount of energy needed to move a charged particle

What are other ways to say potential difference

Voltage, Electromotive force

What is potential difference measured in ?

Volts (V)

Greater voltage= ___ the flow of electrical current

greater

Resistance

opposed the amount of current flowing through

What is resistance measured in

Ohms

Bigger resistance= ___ current flow, smaller resistance= ___ current flow

smaller, larger

A resistor with a high resistance makes a ___ conductor

poor

Ohms Law Formula

V= I x R

Ohms law states that

Increasing voltage increased current flow, increasing resistance decreased current flow

Electric Power

amount of work done by an electric current

What is electrical power measure in

Watts

Power Law Formula

P= IV

Electrical power in a circuit

the rate at which energy is absorbed or produced within a circuit

In contrast to the Power law, Ohms law is used for

incoming electrical power

What is an example of transforming power into another

The filament in an xray tube converts electrical energy into heat releasing electrons

Electric generator

converts kinetic energy to electrical energy through electromagnetic induction

Electric motor

takes electrical energy and turns it into mechanical energy

How does the XRAY tube induction motor work

the stator receives electric power and turns it into mechanical power at the rotor

What is concept #1

A moving electric charge through a conductor makes a magnetic field

Increasing the current= ___ the magnetic field

increases

Coiling the conductor= ___ power/force

Increases

Where are the fields in a coil concentrated and stronger

Inside the coil

What happens when a current flows through a conductor

a magnetic field surrounds the conductor 

What is a solenoid

conductor wound into a tight helix with an electric current passing through it 

What is concept #2

insert another conductor into the coils to increase the strength more

what did Oersted discover in 1824

current passing through a coil creates a magnetic field

What was discovered in 1831 by Faraday and Henry

a moving magnetic field would induce a current in a conductor

What is concept #3

an induced EMF will cause a current to flow

How can concept #3 happen

• moving a conductor through a magnetic field

• moving the magnet across a conductor

The magnetic field intensity has to be _____

constantly moving

Faraday’s Law

increasing the magnetic field increased induced emf, 1 magnet= 1 force

Increase the speed = ___ the amount of voltage

increases

When you approach ___ degrees, a ___ EMF is induced

90, larger

Transformer

changes amount of voltage and current by increasing or decreasing thevalues

What type of current do transformer use

alternating current

What does a transformer do in a circuit

change the voltage

What is a step down transformer

when there are more coils on primary side than secondary

What is a step up transformer

when there are less coils on primary side than secondary

In a basic transformer, the input side is called the 

primary circuit

What is the primary circuit connected to

the available electric energy source

What does the secondary circuit do

produce modified electric energy

Where is a magnetic field created and induced

Created in primary coil, induced in the secondary coil

A transformer can change the voltage depending on the

ratio of the number of turns in the two coils

Autotransformer

has a single windings around an iron core which does both primary and secondary circuit to adjust kVP as needed

How do TAPS work

once kV is elected by tech, taps move to proper selection point, shooting electrical current 

When kV is elected, the autotransfomer

providers voltage to primary side of filament, provides voltage to primary side of high voltage transforker

Step up transfomer

increases voltage of the 2nd circuit and decreases current

What is an example of a step up transfomrer

high voltage transformer in XR machines

Step down transformer

decreases voltage and increases current

What is an example of a step down transformer

filament transformer

Transformer Law formula

Vs/Vp= Ns/ Np

Turns ratio formula

Ns/Np

If the turns ratio is greater than 1

it is a step up transformer

If the turns ratio is less than 1

it is a step down transformer