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RADT 334

Radiation Physics- unit 2

smallest units of electric charge electrons and protons
positive charges do not move they're trapped inside the nucleus
smallest unit of electric charge electron
coulomb (C) 6.3 x 10^18 electron charges
electrostatic laws unlike charges attract; like charges repel; electric charge of a conductor is concentrated along the sharpest curvature of the surface; electric charge distribution is uniform thru out or on the surface; electrostatic force is directly prop to the product
electrodynamics study of electric charges in motion; conductors, insulators, semiconductors, superconductivity matter
V= IR; I=current (A), R= resistance (ohms)
series circuit all circuit elements are connected in a line along the same conductor
rules for series circuit total resistance is equal to the sum of the individual resistance
parallel circuit elements that are connected at their ends rather than lie in a line along a conductor
rules for parallel circuit sum of the current thru each circuit element is equal to the total circuit voltage
direct current electrons flow in one direction along the conductor; batteries
alternating current first flow in one direction, then in the other direction
electric power measured in watts, P=I^2R; P=power in watts, R=resistance, I=current, V=volts
magnetic domain many accumulations of atomic magnets with dipoles aligned
magnetic field strength is measured in tesla
diamagnetic weakly repelled by either magnetic pole
ferromagnetic strongly attracted by a magnet and can become permanently magnetized; iron, cobalt, and nickel
paramagnetic between ferromagnetic and nonmagnetic, slightly attracted to a magnet and loosely influenced by an external magnetic field; magnetic contrast
magnetic laws every magnet has a north and south pole, unlike poles attract, like poles repel, leave the north, return to the south
Oersted any charge in motion induces a magnetic field
selenoid coil of wire, more intense in center of the wire
increase intensity increase current to coil
decrease magnetic decrease current
Faraday's law strength of the magnetic field, velocity of the magnetic field as it moves past the conductor, angle of the conductor to the magnetic field, number of turns in the conductor
Lenz's law direction of induced electric current opposes the action that induces it, self induction (1 coil), mutual induction (2 coils), primary and secondary
electric generator mechanical energy: turned into electrical energy thru induction
electric motor electric energy is turned into mechanical energy, induction motor takes place in the x-ray tube
transformers transforms electric potential and current into higher or lower intensity; Vs/Vp=Ns/Np, N=number of windings, V=volts
step up transformer turns ratio > than 1; voltage is higher on the secondary side than primary
step down transformer turns ratio < than 1; voltage is lower on the secondary side
voltage and current are inversely proportional
types of transformers closed core, autotransformers, and shell type
closed core transformer laminated layers of iron, reduce Eddy currents
autotransformers iron core, only 1 winding, self induction
shell type most common, operates on mutual winding
self induction 1 coil
mutual induction 2 coils, alternating current in a secondary coil by supplying an alternating current to the primary coil
increase intensity distance decreases
increase energy increase frequency
photons aka quantum, bundle of energy, travels and the speed of light, has electromagnetic properties
amplitude 1/2 range of crest and valley
wave equation wavelength=velocity/frequency
c= lambda*frequency
electromagnetic spectrum radiowaves, microwaves, infrared, visible, UV, x-ray, gamma
visible light identified by wavelengths, smallest segment of electromagnetic spectrum, very low energy and long wavelength
what parts of the electromagnetic spectrum used in x-rays x-rays, visible light, and radiowaves (in MRI)
radiowaves identified by frequency, very low energy, long wavelength
ionizing radiation characterized by the energy of the photon, 2 types x-rays and gamma
difference between x-rays and gamma rays origin
visible light tends to behave more like waves than particles
x-rays tend to behave more like particles than waves
transparent light is transmitted unaltered
translucent light is transmitted but scattered and is reduced in intensity
opaque light is totally absorbed
attenuation reduction in intensity by the scatter or absorption of x-rays as they pass through matter
inverse square law radiation intensity is inversely related to the square of the distance from the source
diagnostic energy range is 30-150 kV
E= hf
law of conservation of matter matter cannot be created or destroyed but can be transformed
law of conservation of energy states that energy cannot be created or destroyed, but can change its form
example of conductor copper and aluminum
example of insulator rubber and glass
example of superconductivity niobium and titanium
velocity of all electromagnetic radiation is 3 x 10^8 m/s
diagnostic ultrasound is not part of the electromagnetic spectrum
the energy of a photon is directly proportional to its frequency
only difference between x-rays and gamma rays is origin
electrification created by contact, friction, or induction
coulomb's law electromagnetic force is directly proportional to the product of the electrostatic charges and inversely proportional to the square of the distance between them
example of semiconductor silicone and germanium
resistors function inhibits flow of electrons
batteries function provides electric potential
capacitors function momentarily stores electric charge
transformers function increases or decreases voltage by fixed amount (only AC)
diodes function allows electrons to flow in only one direction
Ohm's law voltage across the total circuit or any portion of the circuit is equal to the current times the resistance
one watt is equal to 1 A of current flowing thru an electric potential of 1 V.
W=VA or P=I^2R
magnetic susceptibility degree to which a material can be magnetized
nonmagnetic materials wood or glass
diamagnetic materials water or plastic
paramagnetic material gadolinium
ferromagnetic materials iron, nickel, or cobalt
ferromagnetic objects can be made into magnets by induction
si unit of magnet field strength is the tesla or gauss (1 tesla= 10,000 gauss)
electric potential is measured in units of joules per coulomb or volt
radiowaves have very long wavelengths compared to x-rays
refraction deviation of course that occurs when photons of visible light traveling in straight lines pass from one transparent medium to another
electromagnet coil or wire wrapped around an iron core that intensifies the magnetic field
electron spin momentum of a particle of an atom in a fixed pattern
4 properties of electromagnetic energy frequency, wavelength, velocity, and amplitude
what 2 types of invisible light come from the sun infrared and UV
narrow region in the middle of the electromagnetic spectrum extending from approximately 400 nm (blue) to 700 nm (red) visible light
light consists of photons with wavelengths longer than those of visible light but shorter than those of micro waves infrared light
light from the sun is responsible for molecular interactions that can result in sunburn UV
emission have low energy and relatively long wavelength. They are usually identified by there frequency by communication broadcasters radiofrequency Emissions
very short wavelength radiofrequency emissions microwave emission
what emission has the most energy? x-ray, visible light, or an RF photon x-ray
Some regions in the EMS behave like waves and some behave like particles in their interaction with matter. What is this phenomenon called wave-particle duality
unit of measure is use for radiofrequency Hertz
unit of measure is used for visible light meters
unit of measure for x-radiation electron volts
smallest units of electrical charge electrons and protons
what happens to an object when it has two few or to many electrons? it becomes electrified
electric current measured in amperes
electric resistance measured in ohms
formula for ohm's law V=IR
creates a magnetic field any charged particle in motion
electron spin creates magnetic field
magnet classification the origin of the magnetic property
matter can be classified by the manner it reacts with an external magnetic field
any charge induces a magnetic field
to intensify the magnetic field using a solenoid wrap the solenoid around a ferromagnetic material
advantages of using an electro magnet compared to a a bar magent magnetic field can be adjusted by varying the current through its coil of wire
Oersted's experiment with a current running thought a copper wire that effects a compass is the bases for electric motor
Faraday's experiments with the motion of a magnet near a coild wire is the principle of electric generator
considering electromechanical devices, what equipment, through electric current, produces mechanical motion electric motor
considering electromechanical devices, what equipment, through mechanical motion, induces electricity thought a coil of wire electric generator
motor used in an x-ray tube induction motor
Created by: meechthebeech91