Rad Physics Exam 3
how many coils are required for self-induction?
1
how many coils are required for mutual-induction?
2
mutual-induction requires
2 coils of wire present
describe mutual induction
2 coils that is either a step up or step down; causing current to flow in secondary flow from primary flow; still has to run on AC; rotor would be an example
if the primary coil of a high voltage transformer is supplied by 220 V, 2 amps and has 200 turns, and the secondary coil has 50,000 turns: what is the voltage induced in the secondary coil? what is the secondary amperage? what type of transformer is this?
55,000 V .008 A step up
if a transformer has 180 primary turns, 65,000 secondary turns, supplied with 220 volts and 2 amps: the secondary voltage would be: the secondary current would be:
79,444.47 V .005 A
what would a battery be a source of?
EMF
what is the formula to solve for turns ratio?
Ns/Np
what is Ohm's Law?
V=I(R) voltage = current x resistance
a transformer has 10,000 windings on the secondary and 150 on the primary. if the primary voltage is 220 V and the primary current is 5 A, what is the secondary current? A) 75 mA B) 150 mA C) 500 mA D) 5 A
a
a transformer will operate: A) on AC but not DC B) on both DC and AC C) on DC but not on AC D) only on a constant voltage
a
a transformer with a turns ratio greater than 1 is: A) a step up transformer B) a step down transformer C) more susceptible to resistance that results in heat generation D) not susceptible to eddy currents that create a loss of transformer efficiency
a
an autotransformer: A) contains a single coil that serves as both primary and secondary coil B) controls xray tube current C) is a shell type of transformer D) is used to control frequency
a
an electric current will flow if the conductor is in a changing magnetic field. This: A) is known as Faraday's law B) is the statement of the second law of electromagnetics C) was discovered by Lenz D) was discovered by Volta
a
an xray tube filament conducts 4.6 A. the primary current is 200 mA. what is the turns ratio? A) 0.04:1 B) 0.2:1 C) 0.6:1 D) 0.9:1
a
in an electric generator: A) a coil of wire is rotated in a magnetic field B) a transformer is charged C) AC is changed to DC D) chemical energy is converted to electrical energy
a
in an induction motor, an electric current is induced in: A) only the rotor B) only the stator C) both the rotor and stator D) neither the rotor nor stator
a
in an induction motor, only the ____________ rotates A) rotor B) wire loop C) stator D) electromagnet
a
the device designed to measure electron flow in a conductor is known as a(n): A) ammeter B) choke coil C) electromagent D) solenoid
a
the electric current produced by an AC generator has: A) alternating positive and negative intensity B) constant negative intensity C) constant positive intensity D) pulsating negative intensity
a
the experimental link connecting electric and magnetic forces was discovered by: A) Oersted B) Faraday C) Lenz D) Volta
a
the fact that an electric current will be induced to flow if the conductor is in a changing magnetic field: A) is known as Faraday's law B) is known as Ohm's law C) is the statement of the second law of electromagnetics D) was discovered by Lenz
a
the main difference between an AC and a DC electric generator is: A) the commutator ring B) the source of EMF C) a magnet D) a transformer
a
the milliamperage meter in a xray circuit is located between the ________ and the ______ A) step-up transformer; xray tube B) step-down transformer; xray tube C) rheostat; rectification system D) autotransformer; timer
a
the milliamperage meter in a xray circuit is located between the _____________ and the ___________ A) step-up transformer; xray tube B) step-down transformer; xray tube C) rheostat; rectification system D) autotransformer; timer
a
the term electromagnetic induction refers to the production of: A) a magnetic field B) a static charge C) is the statement of the second law of electromagnetics D) was discovered by Lenz
a
the transformer: A) changes electric potential and current to higher or lower intensities B) can operate on both AC and DC currents C) does not use mutual conduction D) converts one form of energy to another
a
the turns ratio is defined as: A) number of secondary windings / primary windings B) primary iron core / secondary iron core C) primary voltage / secondary voltage D) primary windings / number of secondary windings
a
transformers have iron cores to intensify the: A) magnetic field strength B) EMF C) electric current D) electric potential
a
what type of components are used as rectifiers in most modern radiographic units? A) n-type and p-type semiconductors B) rheostats C) choke coils D) valve tubes
a
what type of meter is wired in a series circuit? A) ammeter B) voltmeter C) ohmmeter D) penetrometer
a
when one uses a step-down transformer: A) the primary winding will have more turns than the secondary winding B) the secondary voltage will be greater than the primary voltage C) the selection of xray tube current is accomplished D) the turns ratio will be equal to 1
a
which device in the typical xray circuit is adjusted to select the kilovoltage? A) autotransformer B) step-up transformer C) step-down transformer D) rectification system
a
which of the following devices converts electric energy to mechanical energy? A) motor B) generator C) stator D) rotor
a
which of the following is required for a DC electric motor? A) a commutator ring B) an ohmmeter C) a voltmeter D) an ammeter
a
which of the following is required for a direct current electric generator? A) a commutator ring B) a diode C) a voltmeter D) a source of EMF
a
which of the following would be classified as electromechanical devices? A) generators and motors B) generators and rectifiers C) motors and rectifiers D) transformers and electromagnets
a
what is required for current flow?
a changing magnetic field
in an induction motor: A) both the rotor and the stator may have windings B) neither the rotor nor the stator has windings C) only the rotor has windings D) only the stator has windings
a or d
the filament transformer is
a step-down transformer
what is current measured in?
amps
what is self induction?
an induced current within a conductive coil will oppose the direction of the current that induced it
how do you change voltage going to the primary side?
autotransformer
when we select kVp on the control panel what piece is being changed?
autotransformer
what 2 things operate on self-induction?
autotransformer and rheostat (choke coil)
a coil of wire will: A) conduct AC relatively unimpeded B) conduct DC relatively unimpeded C) experience mutual induction from a battery D) experience mutual induction from DC
b
a difference between self-induction and mutual-induction is that: A) mutual induction is the basis for an electric motor and self-induction is the basis for a transformer B) mutual induction requires two coils and self-induction requires only one C) only self-induction can create electromotive force (EMF) D) self-induction requires two coils and mutual induction requires only one
b
a transformer has 10,000 windings on the secondary and 150 on the primary. if the primary voltage is 220 V and the primary current is 5 A, what is the secondary voltage? A) 1.1 kV B) 14.7 kV C) 147 kV D) 110 V
b
a transformer with a turns ratio of 1000:1 is: A) a step-down transformer B) a step-up transformer C) an autotransformer D) used to increase current
b
in an induction motor, an EMF is supplied to: A) only the rotor B) only the stator C) both the rotor and stator D) neither the rotor nor stator
b
primary to secondary coupling in a transformer is enhanced by: A) AC B) an iron core C) DC D) EMF
b
the electric current intensity produced by a DC generator is: A) constant and in one direction B) pulsating and in one direction C) constant and changing direction D) pulsating and changing direction
b
the electric generator is most closely associated with experiments conducted by: A) Edison B) Faraday C) Lenz D) Oersted
b
the magnetic field produced: A) by a solenoid is more intense than that produced by an electromagnet B) in a transformer is based on mutual induction C) in an electromagnet is most intense in the plane perpendicular to its axis D) by an AC source is constant
b
the main difference between an AC and a DC electric generator is: A) a transformer B) a commutator ring C) a magnet D) a source of EMF
b
the principal advantage of an electromagnet over a solenoid is magnetic field: A) polarity B) variability C) homogeneity D) intensity
b
to avoid the hazard of electrical shock, which part of the xray circuit is grounded? A) primary side of the step-up transformer B) secondary side of the step-up transformer C) primary side of the filament transformer D) secondary side of the filament transformer
b
to produce 97 kVp from a 120-V source would require a turns ratio of approximately: A) 99:1 B) 800:1 C) 1100:1 D) 9900:1
b
what is the transformer that looks like a square donut called? A) auto B) closed-core C) induction D) shell-type
b
what type of current is usually found between the secondary side of the high-tension transformer and the rectification system? A) high-voltage DC B) high-voltage AC C) low-voltage DC D) low-voltage AC
b
which of the following is not required for an electric generator? A) a north pole B) source of EMF C) magnet D) a transformer
b
which of the following statements about generators and motors is true? A) they are electromagnets B) they convert energy from one form into another C) they have both primary and secondary windings D) they require direct electric contact between primary and secondary coils
b
which of the following statements about transformers is correct? A) if there were equal numbers of primary and secondary coil turns, the turns ratio would be zero B) laminated transformer cores are more efficient than unlaminated ones C) the autotransformer controls current D) the high-voltage transformer in an xray machine is the autotransformer
b
where is the mA meter located?
between the secondary coil and the tube
Lenz's law states that: A) an electric current will be induced to flow in a circuit if some part of that circuit is in a magnetic field B) there are 2 basic types of induction: primary and secondary C) the current induced in a coil by a moving magnet produces a magnetic field opposite the motion of the magnet D) the right hand rule is used to determine the induced current direction
c
a battery: A) converts chemical energy into mechanical energy B) is a source of electrical resistance C) is a source of electromotive force D) is based on the magnetic property of similar metals
c
all of the following xray circuit devices are located between the incoming power supply and the primary coil of the high voltage transformer except the A) timer B) kV meter C) mA meter D) autotransformer
c
an autotransformer: A) is an electromechanical device B) is a shell type transformer C) contains a single winding to serve as both primary and secondary coils D) is used only to increase voltage
c
an induction motor is used in an xray machine to: A) vary voltage B) control current C) rotate the anode D) provide rectification
c
electromotive force (EMF): A) is an electrical-mechanical force B) is expressed in joule C) is expressed in volt D) stands for electromagnetic field
c
electrons in motion are known as: A) friction B) electrostatics C) electricity or electromagnetism D) a changing magnetic field
c
given a closed loop of wire with no electron flow, an electric current can be induced if: A) no magnetic field is present B) a constant magnetic field is present C) a changing magnetic field is present D) the loop is opened
c
if 2 coils are placed near each other and a varying source of EMF is passed through the first coil: A) electromagnetic radiation will be produced B) self induction will occur in the second coil C) mutual induction will occur in the second coil D) such an arrangement is a solenoid
c
if a transformer produces a large secondary current from a small primary current: A) power will be increased B) the turns ratio will be greater than 1 C) the turns ratio will be less than 1 D) the voltage will be larger on the secondary side than on the primary side
c
in an induction motor, the only part to rotate is the: A) cathode B) electromagnet C) rotor D) stator
c
the output current in a step-up transformer is: A) higher than the input current B) independent of the turns ratio C) lower than the input current D) the same as the input current
c
the principal difference between self induction and mutual induction is that: A) mutual induction is the basis for an electric motor and self induction is the basis for a transformer B) self induction requires 2 coils and mutual induction requires only 1 C) mutual induction requires 2 coils and self induction requires only 1 D) there is no difference
c
the term electromagnetic induction refers to the production of: A) a magnetic field B) a static charge C) an electric current D) an electromagnet
c
the term electromagnetic induction refers to: A) electromagnetic radiation B) a magnetic field C) an electrical current D) a static charge
c
the transformer that resembles a square donut is called a/an ______________ transformer A) auto B) induction C) closed core D) shell type
c
the turns ratio of a transformer is: A) a measure of the power of a transformer B) the ratio of the number of primary windings to the number of secondary windings C) the ratio of the number of secondary windings to the number of primary windings D) zero for an autotransformer
c
the voltaic pile: A) consists of a magnet and a conductor B) consists of a pile of charges C) consists of zinc and copper plates sandwiched together D) is a modern dry-cell battery
c
what device must be adjusted to change the voltage flowing to the primary side of the step-up transformer in an xray generating circuit? A) choke coil B) rectifier C) autotransformer D) rheostat
c
when an AC source is connected to a coil: A) the current flow through the magnetic field changes direction B) electromagnetic radiation will be produced C) mutual induction occurs D) a front EMF will be produced
c
which of the following is based on electromagnetic induction: A) radio reception B) battery C) solenoid D) DC current
c
three types of transformers: which is most efficient? which is the "doughnut" transformer
closed core, autotransformer, shell type; shell type transformer; closed core transformer
which parts are located on the primary side?
control console: line monitor, autotransformer, line compensator, major kVp selector, minor kVp selector, kVp meter, mA selector, timing circuit and selector
what does a rectifier do?
converts AC to DC
what does a motor do?
converts electrical energy to mechanical energy
what does a generator do?
converts mechanical energy into electrical energy (wind turbines)
what does the ammeter measure?
current/ electron flow
a transformer "transforms" or changes electric: A) frequency B) power C) resistance D) voltage
d
a transformer has 10,000 windings on the secondary and 150 on the primary. if the primary voltage is 220 V and the primary current is 5 A, what is the turns ratio? A) 1.5:1 B) 4.1:1 C) 44:1 D) 67:1
d
a transformer with 20 turns on the primary coil and 100 turns on the secondary coil and an input voltage of 220 V would have an output voltage of: A) 4.4 V B) 4.4 kV C) 11 V D) 11 kV
d
an electron moving in a conductor will: A) cause the conductor to behave as a bar magnet B) cause the conductor to bend C) produce a magnetic field in the conductor D) produce a magnetic field perpendicular to the conductor
d
an induction motor is used in an xray imager to: A) control current B) measure mAs C) provide rectification D) rotate the anode
d
if DC is applied to the primary coil of a step-up transformer, what is the result in the secondary coil? A) increased current B) increased magnetic field C) increased voltage D) nothing
d
if DC is applied to the primary coil of a transformer: A) a secondary voltage will result B) a secondary current will result C) a magnetic field will be produced D) nothing will happen
d
in an electric motor: A) a coil of wire is mechanically rotated B) a commutator ring is not necessary C) a transformer is discharged D) AC is changed to DC
d
in electric generators and motors, the commutator ring acts as a: A) source of EMF B) converter from DC to AC C) device to vary voltage D) switch
d
in electric generators and motors, the commutator ring is: A) a device to vary current B) a device to vary voltage C) a source of EMF D) a switch
d
the electric current intensity produced by a DC generator is: A) constant and changing direction B) constant and in one direction C) pulsating and changing direction D) pulsating and in one direction
d
the electric current produced by an AC generator has: A) constant intensity B) pulsating positive intensity C) pulsating negative intensity D) alternating positive and negative intensity
d
the experimental link connecting electric and magnetic forces was discovered by: A) Edison B) Faraday C) Lenz D) Oersted
d
the magnetic field produced by a electromagnet: A) has only a north pole B) has only a south pole C) has neither a north or south pole D) is similar to that produced by a bar magnet
d
the principal application of a transformer in an xray imager is to: A) change AC to DC B) change DC to AC C) change frequency D) change voltage
d
the transformer "transforms" or changes electric: A) impedance B) resistance C) power D) voltage
d
the transformer changes: A) electric current to voltage B) electric energy to mechanical energy C) mechanical energy to electric energy D) the amplitude of the voltage
d
the turns ratio is defined as: A) primary voltage + secondary voltage B) secondary amperage + primary amperage C) primary windings/ secondary windings D) secondary windings/ primary windings
d
transformers have iron cores to intensify the: A) electric current B) electric power C) electric voltage D) magnetic field
d
when an electric current is induced by mutual induction, such current flows: A) according to Oersted's law B) according to Lenz's law C) in the primary coil D) in the secondary coil
d
when designing a transformer, the change in current across it is: A) dependent on the supply voltage B) directly proportional to the voltage change C) in the same direction as the voltage change D) inversely proportional to the turns ratio
d
which of the following is a transformer design used in xray imagers? A) capacitor type B) filament type C) rectifier type D) shell type
d
if a transformer increases voltage 10x, what happens to current?
decreases by 10x (1/10); opposite directions at the same magnitude
is voltage direct or inverse?
direct
what does EMF stand for?
electro motive force
which direction do electrons flow outside a battery?
goes from the positive to the negative
the secondary side of high voltage transformer is
high voltage AC
which parts are located on the secondary side
high-voltage section and xray tube: mA meter, rectifiers, and focal-spot selector
what does a transformer do?
increases or decreases voltage
is current direct or inverse?
inverse
transformers contain what?
iron cores
what is a rectifier?
it only allows electrons flow in one direction; converts AC to DC
the autotransformer gets adjusted to change
kVp
what do the iron cores in transformers intensify?
magnetic field to cause more voltage on secondary side
what is Faraday's law?
mutual induction
if a switch is open is there or is there not current flow?
no current flow (like turning a light switch off)
an autotransformer has
only 1 coil that operates as both primary and secondary
which directions do electrons flow inside a battery?
originate in negative side and go to positive side
an xray machine draws 80 amps of current and is supplied with 200 volts. how much power is consumed?
p= 16,000 W
is the voltmeter wired in series or parallel?
parallel
how do you calculate resistance?
resistance = voltage/current
what does an induction motor do?
rotates the anode
how do you solve for transformer's law
secondary/ primary
what is the turns ratio formula?
secondary/ primary
what is Lenz's law?
self induction
what are the n type and p type?
semiconductor diodes
is the ammeter wired in series or parallel?
series
what kind of rectifiers are used today?
solid state diodes such as p type and n type
if a high voltage transformer has 180 primary turns, 65,000 secondary turns, supplied with 200 volts and 4 amps: what type of transformer is it? the secondary voltage would be: the secondary current would be: what is the resistance of the circuit supplying the power?
step-up 72,222 V .011 A 50 ohms
how do you tell if it's a step-up or step-down transformer
step-up: - ratio > 1 - numerator > denomanator - more coils on the right side step-down: - ratio < 1 - numerator < denomanator - more coils on the left side
what is located on the primary side of the xray circuit?
the line monitor, autotransformer, line compensator, major and minor kVp selector, kVp meter, mA selector, timing circuit and selector
what is located on the secondary side of the xray circuit?
the mA meter, focal-spot selector, and rectifiers
what is conservation of energy?
the power on primary side of transformer= power on secondary side of transformer
what is EMF?
voltage
BONUS what is a compound fracture?
when the bone breaks the skin
BONUS what is an avulsion fracture?
where a piece of bone is ripped off the bone
does the strength of the magnetic field have anything to do with how much current can flow?
yes Faraday's law
if a switch is closed is there or is there not current flow?
yes there is current flow
