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# S1 Equip Unit 2

### S1Unit2 Hooi SJC Electrostatics, Electromagnetic Radiation, Circuits

What's this?Pfffttt... I knew that.
Photon (Quantum) elementary particles of light or radiation traveling at the speed of light. Has both wave and particle properties (interacts with matter by transferring the amount of energy)
Velocity of X-rays (speed of light) = ________________ miles per second or ______________ meters/second in a vacuum. 186,000 miles/second OR 3 x 10^8 meters/second. Represented by symbol (c)
Diagnostic range of energy ~20-30 to150 keV (20-30 in class, 30 in the book)
Define: Wavelength The distance from any point on the sine wave to the next corresponding point. eg: from crest to crest, from valley to valley
The _____ the wavelength, the ______ the energy it has. Longer=less, shorter=more
Define: Frequency The number of wavelengths (number of crests or number of valleys) passing a point per second.
Higher frequency means _______ wavelength and ______ energy Shorter, more
Lower frequency means _______ wavelength and ______ energy Longer, less
Frequency is measured in _____. Hertz (Hz) 1 Hz = 1 cycle/second
Define: Amplitude ONE-HALF the range from crest to valley over which the sine wave varies - from the midline to the crest, or from the midline to the valley. NOT FROM CREST TO VALLEY
At 69.5 kVp and above, ________% of the x-ray beam consists of k-shell Characteristic x-rays ~15% NO K-shell Characteristic x-rays exist below 69.5 range
What energy level can produce Bremsstrahlung x-rays? All energy levels
What percent of x-rays are Bremsstrahlung below 69.5 kVp? 100% (in class she says ~69-69.5)
What percent of x-rays are Bremsstrahlung above 69.5 kVp? 85% Bremsstrahlung x-rays
Define: Differential Absorption The difference between Photoelectrically absorbed x-rays and ones that pass through to the image receptor (scatter and no interaction). "Contrast"
What 3 types of x-ray interactions with matter are important to making a radiograph? Compton Scatter, Photoelectric Absorption, Photons Transmitted without Interaction
As x-ray energy increases, Compton Scatter __________ Decreases slightly, but does not reach zero
As x-ray energy increases, Photoelectric Interaction ________ Decreases much faster than Compton Scatter (also consider the type of tissue being penetrated, soft tissue drops off more quickly than bone or contrast material)
As x-ray energy increases, Transmission (without interaction in the body) ________ Increases
Define: Electrostatics The study of stationary electric charges
Define: Coulomb One unit of electrostatic charge = 6.3 x 10^18 Electrons
One unit of positive charge (______) and one unit of negative charge (_______) have the same _________ but opposite _________ (Proton), (Electron), Magnitude, Signs
Static Electricity The study of stationary electric charges
An object is said to be __________ if it has too few or too many electrons. electrified
Static Electricity is generated by ________ the molecular arrangement of relatively non-conductive insulators unbalancing
What are three ways to Electrify an object? Friction, Contact (conduction), Induction
Define: Electrostatic Discharge the "release" of built up static electricity from an electrified object
Define: Friction Friction occurs when two substances are rubbed together
Define: Contact (conduction) The transfer of energy from one object to another through a transmission medium.
Define: Induction The transfer of energy from one object to another without the objects touching.
Coulomb's Law Electrostatic force is directly proportional to the product of the electrostatic charges and inversely proportional to the square of the distance between them. (See equation)
5 principles of Coulomb's Law 1) Charged particles have a field that radiate out from a positive charge 2) and in towards a negative charge 3) like charges repel one another 4) unlike charges attract one another 5) uncharged particles do not have a field
Define: Electrodynamics The study of charges in motion
Define: Electric Current Electric current moving along a conducting object. Measured in Amperes (A)
Ampere one unit of electric current (A). 1A = 1 Coulomb (C ) of charge flowing through a conductor each second. A=C/s
Current flows from ______ to ________ negative, positive
Conductor Any substance through which electrons flow easily.
Insulator Any substance that does not allow electron flow.
Semiconductor a material that under some conditions behaves as an insulator and in other conditions behaves as a conductor.
Electric Circuit When resistance of a conductive material is controlled and made into a closed path.
Electric Potential "stored energy" measured in volts. 1V= 1Joule/Coulomb. When positioned close to each other, like electric charges have ELECTRIC POTENTIAL ENERGY because they can do work when they fly apart.
Potential Difference The difference of electrical potential between two points.
Voltage "Electromotive Force" the "push" behind the current to make it move. It is caused by potential difference and is the quantitative expression of potential difference.
Resistance Measured in ohms. Resistors determine the amount of current through an object for a given voltage across that object.
Ohm's Law V = I R where V is the electric potential in volts, I is the electric current in amperes, and R is the electric resistance in ohms.
Series Circuit All circuit elements are connected in one following another in a ring. Voltage and resistance are additive. Amperage is constant, meaning that current through each circuit element is the same (like a string of lights)
Parallel Circuit Contains elements that bridge conductors rather than lie in a line along a conductor. The amperage (current) is additive and the voltage is constant. The total resistance is the inverse of the sum of the reciprocals of each individual resistance.
Power Law P = IV Where Power (watts) = Current (amps) x Voltage (volts)
Created by: paigeduh