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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
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