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Rad 121 Chapter 5 Electricity, Magnetism, and Electromagnetism
x-ray imaging system coverts ____ into ____
electric energy into electromagnetic energy
the study of stationary or fixed electric charges is known as?
what are the five laws of electrostatics?
4)inverse square law
force between 2 charges is directly proportional to the product of their charges and inverserly proportional to the square of the distance between them is known as?
Charges reside on the external surface of conductors is known as?
Concentration Law: greatest distribution of charges on surface on ________ curve?
process of electric charges being added/subtracted from an object is known as what?
objects rub against one another and electrons travel from one to the other is known as?
two objects touch; electrons move from one object to another is known as?
Contact causes _______ of charges?
process of electrical fields acting on one another w/o contact is known as?
it is the most important method?
induction method used in the operation of _______devices?
study of electric charges in motion is known as?
movement of electrons or electricity results from the traveling of ______?
only _____ charges move along solid conductors
Positive charges are fixed in the ?
electrons move from _____ to _____ concentration
highest to lowest
______charge=object with more electrons
_____charge=object with weaker negative charge or an object with fewer electrons than another object
electric current travels from _____ to _____ poles
postive to negative
electric /electron flow travels from ____ to ____ poles
negative to positive
electric current occurs in:
1)vacuum (x-ray tube)
3) inonic solutions & metals
any substance through which electrons flow easliy is known as?
Examples of conductors:
materials that resist electron flow is known as?
good insulators are:
materials with the ability to conduct electricity under certain conditions and insulate under other conditions is known as?
Two examples of semiconductors are:
silicon and germanium
allows electrons to flow freely w/no resistance below certain temperatures is known as?
superconductivity works with what kind of temepratures?
very cold (liquid nitrogen)
two examples of superconductivity is?
noibiun and titanium wire which are used in MRI
Nature of electron flow is?
1)direction of electron travel
2)quantity of electrons flowing
3)force of electron travel
4)opposition to current flow
what are the two currents for direction of electron flow?
Direct current (DC)
Alternating current (AC)
all electrons travel in the same direction is what type of current?
oscillating current is what type of current?
Quantity of electrons flowing=
quantity is measured in what unit of current?
Ampere = A
x-ray is measured in what unit?
causes number of electrons and x-rays produced to vary is known as what?
force of electron tavel=
electric potential exists when the flow of electrons has?
unit of electric potential is?
electric potential determines the speed of electrons that determines penetrability which developes what?
amount of opposition to current flow is =
resistance or impedance
opposition is measured in
unit of resistance is called?
what are the 3 factors that impede the flow of electrons?
1)Length of the conductor
2)crosssectional diameter of the conductor
3)temperature of the conductor
Length of the conductor-as length doubles, resistance does what? and has what proportional relationship?
crosssectional diameter of the conductor-as diameter doubles, resistance does what? and has what type of relationship
temperature of the conductor-
causes increase or decreases of resistance depending on conductor, insulator or semiconductor
electric potential is sometimes called
unit of electric potential is
V for US household is
Electric power is known as
rate of doing
Electric power is measured in
electric power-Household appliances tend to operate between
500 to 1500w
x-ray machines require kW (electric power)
20 to 150kW
x-ray machines require V (electric potential)
Ohm's law is a interrelationship of
current, potential, and resistance
for Ohms law voltage across the total circuit is equal to the
current x resistance
what is the Ohms law equation
electric potential in volts
current in amperes
resistance in ohms
electric power formula
P=current x voltage
formed by controlling the resistance in the closed path of a conductor is known as?
all circuit elements are conected in a line are known as
what are some advantages to series circuits?
cheap, easy to fix, repair, replace. greater potential difference=greater total voltage. current remains the same
what are some disadvantages to series circuits?
all resistances have to be operable. failure of one=the whole supply. resistance increases
each element has an individual branch is known as
what are some advantages to parallel circuits?
elements can operate at lower voltage bc voltage doesnt change. failure of one element doesnt interrupt the other . resistance goes down
whart are some disadvantages to parallel circuits?
current increases, can over head=fire
what are 2 safeguards that break the circuit before a dangerous temeprature is reached?
fuse, circuit breaker
metal tab that melts with increased heat is known as?
pops open and can be reused and reset
the voltage across the total circuit or any portion of the circuit is equal to the current time the resistance
Ohm's Law equation
A material that when combined with some other material can be turned into an insulator or a conductor.
a substance that readily conducts e.g. electricity and heat
a material that does not allow heat or electrons to move through it easily
what is the coulomb's law equation?