rad tech exam

unit of measurement for energy

eV

Unit of measurement for frequency

Hz (Hertz)

unit of measurement for wavelength

meters (m)

unit of electric charge

Coulomb

unit of measurement for current

ampere, I

unit of measurement for potential difference

voltage, V

unit of measurement for resistance

Ohms (Ω), R

unit of measurement for magnetism

-Tesla (T)

-Gauss (G)

friction

the transfer of electrons by rubbing objects together

contact (conduction)

transfer of electrons by touching an electrified object to another object

Induction

charging an object without it touching another object

what happens to the charge of a neutralized object when it touches a negatively charged object?

it becomes negative

what happens to a the charge of a positively charged object when it touches a negatively charged object?

it becomes neutralized

law of electrostatics

like charges repel, unlike charges attract

negative force

attracts

positive force

repels

Coulomb's Law

The force between two charges is directly proportional to the product of the charges and inversely proportional to the distance between the charges squared

Voltage Formula (Ohm's Law)

V=IR

Current Formula (Ohm's Law)

I=V/R

Resistance formula

R=V/I

electric power formula

P=IV

speed of light (c)

3 x 10^8 m/s

Formula for wavelength when given frequency

Wl= C/F

Planck's constant (h)

4.15 x 10^-15

eV constant

10^3

formula for frequency

f= eV/h

Formula for frequency of a wave

f= C/WL

wavelength shortcut formula

Wl= 12.4/keV

electrodynamics

The study of electric charges in motion

conductor

allows electrons to flow

Insulator, dielectric, nonconductor

inhibits the flow of electrons

semiconductor

acts as both a conductor and insulator

superconductor

allows electrons to pass without resistance

resistance depends on material

-conductor, less resistance

-insulator, more resistance

resistance depends on length of path

increase in length= more resistance

resistance depends on cross sectional area

increase in cross section= less resistance

amount of resistance depends on temperature

increase in temp= more resistance

Voltmeter

a device used to measure voltage, connected in parallel to circuit

Ammeter

a device used to measure current, connected within the circuit

direct current

an electric current flowing in one direction only

alternating current

A flow of electric charge that regularly reverses its direction

what happens to magnetic strength when the field length increases?

it decreases

magnetic permeability

ability of a material to become magnetized

Magnetic retentivity

the ability of a material to stay magnetized

natural magnet

found in nature

Artificial Permanent magnet

man made

Ex: hardened steel, alloy

Electromagnets

A magnet created by electricity

ferromagnetic

matter with strong magnetic properties and strongly attracted to magnets

paramagnetic

materials weakly attracted to a magnetic field

diamagnetic

materials that cannot become magnetized and are weakly repelled by a magnetic field

nonmagnetic

materials unaffected by a magnetic field

law of magnetism formula

D^2/d^2 = x/N

Attenuation

The reduction in the number of x-ray photons in a bean and loss of energy

Refraction

deviation in the line of travel of a light photon

Radiolucent

permitting the passage of x-rays (dark)

Radiopaque

substances that do not permit the passage of x-rays (white)

radiation intensity formula

I/i = d^2/D^2

Capacitor

a device used to store charge in a circuit

capacitance

the ratio of an object's stored charge to its electric potential difference