Study Physics 8.6 - 8.11 Flash Cards

 
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Physics 8.6 - 8.11

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what is the process of inducing an electromotive force into a conductor as it cuts magnetic lines of force
electromagnetic induction
what is the number of cycles per second called in an alternating current
frequency
the total opposition to the current flow in an AC circuit
Impedance
what are the two advantages of AC over DC
AC is needed to operate transformers
less power loss in AC than DC
what are the kinds of losses of electrical power in a transformer
copper losses
Eddy losses
hysteresis losses
what is the efficiency of a transformer
the ratio of the power output to the power input
what type of transformer is the most advanced type, used as a power or commercial transformer
shell type
what type of transformer consists of heavily insulated coils wound around a square or circular iron ring or core
closed core
what type of transformer consists of two types of highly insulated coils lying side by side
air core
what type of transformer consists of an iron core inserted into a coil of wire carrying an eletric current
open core
what are the four types of transformers
air core
open core
closed core
shell type
what is the formula for the conservation of energy for a transformer
IsVs = IpVp
what is the law of conservation of energy for a transformer
there can not be more energy put out of a transformer than what is put in
what is the formula for transformer law
Vs/Vp = Ns/Np
a transformer that has more turns in the secondary coil than in the primary coil is considered to be what type of transformer
step up
a transformer that has more turns in the primary coil than in the secondary coil is considered to be what type of transformer
step down
what are the two types of coils a transformer has
1.primary
2.secondary
what employs the principle of electromagnetic mutual induction
transformers
an electromagnetic device which changes an alternating current from low voltage to high voltage, high voltage to low voltage, without loss of an appreciable amount of electrical energy
transformer
what are the two types of electric motors
direct current motors
alternating current motors
what are the two main types of alternating current motors
synchronous motor
induction motor
what type of motor is used to operate the tilt of the xray table and used to turn the anode of the xray tube
induction motor
what type of motor has a strator and a rotor
induction motor
what is used to determine the direction of the movement of the conductor in an electric motor
right hand motor rule
what two conditions must prevail in the principle operation of the electric motor
1.the conductor must carry a current
2.the conductor must be located in a magnetic field
a device that converts electrical energy to mechanical energy
electric motor
what is the fluctuations of current and voltage as shown on the sine wave
ripple
what is the term used to describe the difference in phase relationship between voltage and current
phase angle
In an AC generator if the current and voltage reach zero together, rise and fall together, and attain peak values together are considered to be what
in phase or in step
In an AC generator if the current and voltage are not in step with each other it is considered to be what
out of phase
what is the formula for ohm's law as it refers to an AC circuit
I=V/Z
the unit of measure for impedance is what
ohm (Z)
if a capacitor is added to an AC circuit and the polarity reverses as the current reverses the amount of hinderance to the flow of current is known as what
capacitive reactance
in a DC circuit what allows current to flow only until it has reached full charge whereupon the current ceases to flow
capacitor
what is the "bucking" tendency of inductance in an alternating current circuit
inductive reactance
the opposition to a change in the amount of current flowing in an alternating circuit
inductance
the factor which, in an AC circuit, causes the impedance to be larger than resistance
reactance
in a sine curve what is the maximum value of a given alteration measured from zero to peak
amplitude
In a sine curve what is the measure of power from a negative peak to a positive peak
peak to peak value
what is the common use in the US for hertz
60 Hz
what is the unit of measure for frequency
hertz
what is the curve called that shows the relationship of the alternating current to the succesive positions of the generator armature as it rotates between the magnetic poles
sine curve
what are the components of a simple generator
field magnet
armature
shaft
collector or slip rings
brushes
what is the device that converts mechanical energy to electrical energy by electromagnetic induction
electrical generator or dynamo
the process of inducing a current flow through a secondary coil by passing a varying current through the primary coil
mutual induction
the induction of an opposing EMF in a single coil by its own changing magnetic field
self induction
what are the two types of induction
self induction
mutual induction
what law states the induced current will flow in a direction such that it opposes the action that induces it
Lenz's Law
what rule is used to determine the direction of induced electric current
left hand or dynamo rule
what are the four factors that determines the number of lines of force cut per second
1. speed with which a conductor cuts magnetic lines of force
2. strength of the magnetic field
3. angle between the conductor & the direction of the magnetic field
4. number of turns in the conductor
the magnitude or size of the induced EMF depends on what
the number of lines of force cut per second or the number of flux linkages per second
what are the three ways to induce an EMF or voltage in a wire by electromagnetic induction
1.the wire may move across a stationary magnetic flux
2.the magnetic flux may move across a stationary wire
3.the magnetic flux may vary in strength while a stationary wire lies in it
what is the interaction between a line of force and a single loop conductor
flux linkage
what determines the strength of the magnetic field in an electromagnet
ampere turns
type of core material
what two factors determines the strength of the magnetic field in a coiled conductor (solenoid)
amount of the current in the coil
the number of turns in the coil
what is a solenoid with an iron core called
electromagnet
what can be predicted with the left hand rule
direction of the magnetic flux inside the coil
which end of the coil will be the north
what is a helix or coiled conductor carrying an electric current
solenoid
if the conductor is grasp with the left hand with the thumb pointing in the direction of current flow, then the fingers encircling the wire will indicate what
the direction of the magnetic lines of force around the current
In magnetic effect, the greater the current flow...
the greater the resulting magnetic field
true or false:
a magnetic field always surrounds a conductor in which an electric current is flowing
true
what is the branch of physics that deals with the relationship between electricity and magnetism
electromagnetism
what is the unit of measure for the capacitance
farad
what is the quanity of electrical charge, in coulombs, stored per volt, applied to the capacitor called
capacitance
what are the three limits of a parallel plate capacitor
size of the plates
distance between the plates
types of diaelectric material
what is connected to the plates of parallel plate capacitor to deliver and recieve current
wiring (conductor)
what is the insulative material placed between the plates of a parallel plate capacitor
diaelectric material
what is the simplest type of capacitor
parallel plate capacitor
a capacitor was formally called a what
condensor
a device for storing electrical energy by virtue of an electrostatic field
Capacitor
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