RAD Physics - Chapter 10

step up transformer

The high voltage that is required by an x-ray machine is produced by the __________.

mutual induction

A transformer works on the principle of ___________.

input, output

The primary coil is the __________ side of the transformer and the secondary coil is the __________ side.

number of turns, number of turns

The transformer law states that the emf induced in the secondary coil is to the emf in the primary coil, as the __________ in the secondary coil is to the __________ in the primary coil.

step up, higher voltage

A __________ transformer has more turns in the secondary coil than in the primary coil and therefore __________ is created in the secondary coil than is supplied to the primary coil.

step down, less voltage

A __________ transformer has fewer turns in the secondary coil than in the primary coil and therefore __________ is created in the secondary coil than was supplied to the primary coil.

energy

According to the law of conservation of energy, there can be no more __________ coming out of the transformer than was put in.

voltage, amperage

A step up transformer increases __________ and decreases __________.

voltage, amperage

A step down transformer decreases __________ and increases __________.

high potential difference

In a diagnostic x-ray machine, the transformer provides the _________ necessary for the electrons to be driven towards the anode with enough speed to create an x-ray photon

kV, mA

The step up transformer of an x-ray machine changes voltage into __________ and amperage into __________,

flux leakage

The leakage of magnetic flux in the air at the ends of the cores of a transformer is known as __________.

efficiency

The ratio of power output to power input of a transformer is known as __________.

copper loss

The loss of electrical power due to the resistance of the coils of a transformer is known as __________.

thicker, thinner

In a step up transformer, the primary winding carries a larger current so the wire must be __________ as compared to the secondary coil which carries a smaller current and therefore the wire may be __________.

eddy current

The swirling current created in the core which is induced by the magnetic flux is called an __________ .

hysteresis loss

The power loss of a transformer due to the energy necessary to overcome the opposition to change, exhibited by ferromagnetic materials, every time the magnetic field produced by the primary winding changes polarity is known as ___________.

autotransformer

The _________ varies input voltage to the transformer in order to control output voltage and therefore functions as the kV selector of an x-ray machine.

incoming power supply, primary

The autotransformer is connected between the __________ and the __________ side of the step up transformer.

self induction

The autotransformer operates on the principle of __________.

primary

The secondary voltage of the autotransformer is applied to the __________ side of the main step up transformer.

filament

The __________ circuit of the x-ray tube carries the current needed to heat the filament.

tube

The __________ circuit of the x-ray tube carries the current passing between the cathode and anode.

choke coil

A __________ is a coil with a core whose position is able to be adjusted, which operates on the principle of self induction and was once used to regulate filament current in the x-ray tube.

rheostat

A __________ is a variable resistor designed to regulate filament current.

air core transformer

two insulated coils of wire side by side

open core transformer

two insulated coils of wire with an iron core side by side

closed core transformer

two coils wound around a square iron core

shell type transformer

primary and secondary coils wound around the central section of a core consisting of sheets of silicon steel with two rectangular cutouts

autotransformer

a single winding that serves as both the primary and secondary coil, with an adjustable number of windings on the secondary side

open core and air core

Which type of transformers have most flux leakage?

closed core

Which type of transformer is most commonly used in x-ray equipment?

yes

Is a transformer considered to be efficient?

by using copper wire of adequate diameter

How can copper loss be reduced?

using laminated silicon steel plates

How can eddy currents be reduced?

x-ray generator

what’s another name for an x-ray transformer?

x-ray transformer

change volts into kilovolts in order for the x-ray machine to create x-ray photons

transformer

device that changes alternating current from low voltage to high voltage and vice versa

higher

Can’t plug x-ray machine into regular outlets (need a ___ voltage)

low, high and high, low

• 2 types of transformers

  • ___ to ___ voltage (increase)

  • Or ___ to ___ voltage (decrease)

air core transformer

simplest type of transformer?

mutual induction

supply the first coil (primary or input) with alternating current, then there is alternating current in second coil (secondary coil or output)

transformer law

if you supply the primary coil with alternating current with some turns, and the secondary side has more turns this means it has an increased voltage (more turns = more voltage)

step up transformer

more turns in the secondary coil (increases voltage, decrease current)

step down tranformer

more turns in the primary coil (decrease voltage, increase current)

current

decrease voltage → increase amperage

open core transformer

improvement on air core transformer

open core transformer

• 2 coils side by side with iron core in the middle of the coils (more powerful)

• Magnetic field lines are closer together

closed core transformer

improvement of open core, so now it has a continuous core

closed core transformer

No more flux leakages, but now we have Eddy currents, we minimize this by laminating it & the core is made of silicon steel. which transformer?

shell type transformer

2 rectangular cut outs (primary and secondary coil are wound around central area)

shell type transformer

Commercial transformer: used in industry

primary, secondary, copper loss

this depends on the true electrical resistance of the wires, which is influenced by their diameter. The side carrying less current uses thicker wire, in a step-up transformer, this is the ___ side, while in a step-down transformer, it’s the ___ side what is this?

eddy currents

swirling currents

hysteresis loss

every time the current changes direction, resistance to north and south poles flipping, minimize by laminating silicon steel

autotransformer

takes the incoming current or voltage and it either increase or decreases the voltage then sends it to step up transformer

single

Autotransformer has a ___ coil that serves as the primary and secondary side of the autotransformer

set, vary

# of turns on the primary side is ___, the # of turns on the secondary side ___ (also called tapped turns)

up

The voltage that comes out of the primary transformer is fed to step ___ transformer

kv

Autotransformer is the ___ selector

penetration power

Kvp controls ___ of our x-ray photons

more

Thicker part need ___ penetration (high kVp)

less

Thinner part ___ penetration (low kVp)

filament circuit

provide the current to heat the filament

tube circuit

provide the big potential difference across the tube, which makes the cathode (-) and anode (+), so it can produce x-ray photons

tube current

actual electrons traveling from cathode to anode (filament to target)

filament current

 the current that heats the filament

small, large

A ___ change in filament current, produces a ___ change in tube current

choke coil

(the old method) coil of wire with removable core

self induction

Choke coil operates on the principle of ___

current

If core is in coil we have the least amount of ___

rheostat

(newer version) variable resistor

less

More resistance, the ___ flow of current going to filament to heat it up

mA

Rheostat is the ___ selector