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Rad Physics Unit 3

Terms in this set (21)

Nature of electricity
1.) Current
2.) Voltage - electromotive force & potential difference
3.) Electrical resistance
Unit of measurement of an electric current
ampere - which measures the AMOUNT of electrons flowing in an electric current ( the more electrons flowing per second = a stronger current)
Electromotive force
The force with which electrons move in an electrical circuit - aka potential difference
Unit of measurement for electromotive force or potential difference
Volt
Potential difference
A difference in positive or negative charge that creates an electrical pressure. This pushes the electricity from the negative charge and pulls it towards the positive.
The higher the potential difference
the higher the energy of the x-rays produced. ex) 90 kVp will produce a higher energy than 70 kVp
Electric resistance or load
That property of the circuit which opposes or hinders the flow of an electrical current.
Unit of measurement for electric resistance
ohm
Good conductors
Copper, aluminum, water
Poor conductors - insulators
Rubber, glass, wood
The resistance of a conductor is ____________ to the length of the conductor
Directly proportional
Resistance of a conductor is ____________ to the cross-sectional area
Inversely proportional - think of putty being pushed through a large whole versus a small hole
Resistance becomes _____________ as temperature rises
greater
Ohm's law
The voltage across the total circuit or any portion of the circuit is equal to the current times the resistance
Grounding
A protective measure to neutralize an electric charge and is a process of connecting the electrical device to the earth via a conductor.
Positively charged objects...
take on electrons from the earth, while negatively charged objects give up electrons to the earth until they are neutralized
Ground potential equals
ZERO
Alternating current
An electrical current in which the flow of electric charge (electrons) periodically reverses direction. (electric power that is delivered to businesses and residences)
Direct current
Electrons flowing in one one directions in a conductor. (battery)
Pulsating direct current
A direct current that changes in value at regular or irregular intervals - xray tube operates on direct/pulsating direct current so the current only goes in one direction (cathode to anode)
Transformer
A transformer changes electric voltage into higher or lower values - if voltage goes up, amperage goes down
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