EXAM 2

rad151

ohm’s law

Voltage in an electric circuit is equal to the current multiplied by the resistance

potential energy

stored energy of an object due to it’s position, shape, or arrangement of parts

Which electron shell has the most and/or the least amount of binding energy?

least=further from nucleus

most=closest to nucleus

relationship of electrons and their binding energy

attachment between the orbiting e- and the nucleus

kinetic energy

energy and object has due to its motion

wave equation

c= freq. times wavelength where c= 3×10^8

unit for electrical resistance

ohm

ohm’s law equation (2 forms)

1. V=IR

2. P=IV

P=power

V=potent. diff. in volts

I=current in amp

R= resistance in ohm

V=IR

ohm’s law

P=IV

also ohm’s law

P in ohm’s law=

power

V and I in ohm’s law=

v=potential difference measured in volts

i=current measured in amperes/amp

R in ohm’s law=

resistance measured in ohm’s

What is tungsten?

90% tungsten, 10% rhenium:(

The metal in the filament (cathode) is used as the target (Anode) due to its high melting point

What metals could be melted with tungsten to improve it?

thorium

possibly rhenium so keep that in mind too but def thorium

electric generator

converts mechanical energy into electric energy, and produces electric current via rotating loops of wire through a fixed magnetic field

electric generator vs. electric motor

electric generator=mechan. to elect. energy

motor=elect. to mechan. energy

What direction does conventional current flow?

Positive to negative

T/F, non-ionizing radiation possesses enough kinetic energy to eject electrons (e-).

False

T/F, the anode has a positive charge.

True

T/F, the cathode has a negative charge.

True

_______ flows from anode to cathode.

current

_______ flows from cathode to anode.

electrons (e-)

P-type crystals have an abundance of..

electron traps

N-type crystals have an abundance of…

free moving electrons

P vs. N type crystals

P= electron traps

N=freely moving electrons

If wavelength increases, what happens to frequency?

decreases

actual focal spot

actual-area of target struck by filament electron(on anode, large)

effective focal spot

x-ray beam from patients perspective (small for higher detail)

T/F, the effective focal spot is small.

True

T/F, the actual focal spot is small.

false

What does “sun tanning” of an aging X-ray tube indicate?

vaporized tungsten/tungsten build up

What is leakage radiation?

radiation produced in directions other than the target window and escapes protective housing

Transformer Law

Voltage and the number of turns are directly proportional

transformer law equation

voltage times secondary coil divided by voltage times primary coil=number of turns times secondary coil divided by number of turns times primary coil

SI unit for frequency

Hz/Hertz

List 3 basic types of magnets.

1. natural

2. artificial permanent

3. electromagnetic

Lodestones are a part of…

natural magnet

Steal and alloy is a part of…

artificial permanent magnet

an iron bar wrapped with wire is a part of…

electromagnet

What are Earth’s magnetic poles?

south and north

Earth’s MAGNETIC south pole sits next to Earth’s GEOLOGICAL _______ pole.

north

Earth’s magnetic North pole sits next to Earth’s geological ______ pole.

south

What is the relationship between magnets and their poles?

north pole is attracted to the south pole

thermionic emission

release of electrons from heated filament/process of e- being boiled off

In thermionic emission, more current =_____ which then =

more current=hotter=more e- boiled off

rheostat

controls resistance in a filament, amount of heating, and ultimately # of electrons being boiled off in thermionic emission

The primary circuit is considered ______ voltage.

low, 220 v

Secondary circuit is considered ______ voltage.

high

3 reasons we use tungsten in an X-ray tube.

1. high atomic number (74)

2. Good thermal conductivity

3. high melting point

Which parts of the anode and cathode are on the X-ray tube

cathode:filament, focusing cup, filament

anode: target, focal spot, rotor/stator, molyb.

What are monopoles and dipoles a part of?

magnetic domains

electromagnitism

monopoles have a(n) ______ field.

electric

dipoles have a(n) _____ field.

magnetic

monopoles vs. dipoles

Monopoles face outward, are linear, and could exist alone,

while dipoles are curved, form a closed loop, and contain north and south poles.

magnetic domain

when a group of dipoles (atomic mag.) align with each other

this represents a _____________ ripple.

100% half-wave

this represents a ___________ ripple.

1% or less high-frequency

what % ripple do high-frequency, fully rectified waveforms and X-ray tubes have?

less than 1 %

What is the issue with a single-phase, fully rectified wave?

100% ripple and varying energy

what happens when the transformer changes?

voltage and current also change

how does an x-ray tech control number of x-ray photons on a console?

mA selector

Which is the correct ratio in terms of secondary and primary coils?

1. primary: secondary

2. secondary:primary

2. secondary to primary

1000:1 indicates a step-____ transformer.

step up

1:1000 indicates a step-____ transformer.

step-down

Stators and rotors create magnetic fields in what type of motor?

induction motor

which has an iron core with coils of wire?

rotor

which is made up of several electromagnets?

stator

step-up transformer _____ voltage.

increases

step-down transformer _____ voltage.

decreases

Fleming's right-hand rule.

Right thumb points the direction of current flowing through wire and ur finger tips point in direction of mag. flux around wire

what is flemings right hand rule used to determine?

direction of mag. flux

components of electromagnetic force

electricity and magnetism

How does conventional current flow?

positive (anode) to negative (cathode)

electric motor

Converts electrical energy into mechanical energy

How does AC turn into DC in an electric generator?

rectification/rectifier

how do you get electrons to flow along a conductor?

excess of positive charges on one end and excess of negative charges on the other bc opposites attract

atomic # of tungsten and what does it do

74, improves efficiency of x-ray production

type of metals used in an x-ray tube

1. tungsten

2. rhenium

3. copper

4. nickel

5. thorium

6. cobalt

mA to amps

divide by a thousand

kV to volts

multiply by a 1000

1MHz = _______ Hz

1,000,000 Hz

P= _ times _

P=IV

P= in units

watts

v=

volts

i=

amps

r=

ohm