Physics Unit 3 Flashcards
What term is used to describe how easily materials can be magnetized?
Permeability
A material that cannot be magnetized because the electrons all spin in different directions is called a_____ material
Non-magnetic
When using the left hand thumb rule for straight conductors, the fingers encircling the wire indicate
Direction of magnetic field
Materials that are weakly repelled by magnets area classified as what type of magnet
Diamagnetic
The term “electromagnetic induction: refers to the production of
An electric current
Ferromagnetic
Iron, cobalt, and nickel
Nonmagnetic
Wood, plastic, and glass
Diamagnetic
Beryllium, bismuth, and lead
Paramagnetic
Gadolinium, platinum, and aluminum
The north pole of a magnet will be attracted to the north pole of another magnet
False
T/F no matter how many pieces a magnet is cut into, each piece will have a north and south pole
True
T/F the more closely spaced, the lines of magnetic flux, the weaker the field
False
Which person discovered electromagnetic induction
Faraday
Which of the following types of magnets are considered temporary
Electromagnets
The more coils or numbers of turns a conductor has, the _____ the electromagnetic force
Greater
The unit of measurement of magnetic flux is the
Weber
Lines of force, on the external surface of a magnet, move from the___pole to the _____pole
North, south
A coiled helix, carrying an electrical current is known as a
Solenoid
What is the difference between an electromagnet and solenoid?
An electromagnetic has a ferromagnetic core, and a solenoid has no core
In a straight conductor, when the conventional current is flowing out of a piece of paper, lying on the table, what direction will the magnetic field be traveling?
Counter clockwise
Which of the following statements is true regarding the strength of induced current
The faster the conductor, the stronger the current
What principle does the auto transformer work?
Electromagnetic self induction
What device varies the voltage that will go to the step up transformer
Auto transformer
What is the difference between a step up transformer in the auto transformer?
The auto transformer only has one coil
Where is the auto transformer located?
Between the incoming AC and the high voltage transformer
There are two separate circuits, supplying the x-ray tube. Which one carries the amperage needed to heat the filament.
Filament circuit
Of the two circuits, supplying the tube, which one applies the necessary potential difference across the tube that makes the electrons race from cathode to anode
Filament circuit
And auto transformer with primary turns, and 1000 secondary turns, has a turns ratio of
1:2
What device is used to increase the amperage to the filament?
Step down transformer
What device is used to increase the voltage to kilovoltage ?
Step up transformer
What is the terms ratio if a transformer has 40 primary turns and 80 secondary turns
2:1, 80:40
A transformer with fewer turns on its secondary coil is a
Step down transformer
An auto transformer;
Varies the voltage going to the high voltage transformer
An auto transformer can be considered a
KV selector
The most efficient type of transformer construction utilized in x-ray equipment is the
Shell type
A dynamo is another name for a/an
Electric generator
How do generators create energy?
Electromagnetic induction
The stronger the magnetic lines are in an electrical generator the;
Stronger the induced current, & the closer the flex lines around the magnet
Slip rings and brushes can be found in
An AC generator
A generator converts
Mechanical to electrical energy
T/F The voltage on the secondary side of a step down transformer is less than on the primary
True
T/F the amperage on the secondary side of a step up transformer is greater than on the primary
False
T/F the strength of the induced voltage in the secondary coil of a transformer is directly proportional to the number of turns it has in its coil
True
T/F a step down transformer, has a turns ratio of greater than one
False
T/F a transformer, if you increase voltage, you must increase amperage
False
T/F transformers, can operate on AC and DC
False
T/F current stays in a constant direction in an AC circuit
False
What device in the x-ray machine uses an induction motor
Rotor
The type of rectification, where no actual rectifier is added to the circuit is
Self rectification
Half wave rectification is inefficient because
It uses only half the available energy of the AC
Half wave rectification can be accomplished by using____ or___ diodes
One or two
Full wave rectification uses a minimum of_____ solid state diodes to rectify the entire AC in usable energy
4
A single phase, fully rectified unit has how much ripple
100%
A three phase, 6-pulse fully rectified unit has how much ripple
13%
How much ripple does a high frequency, fully rectified unit have
Less than 1%
Full rectification uses____ of the available AC
All
In three phase energy, the waveforms are out of step with each other by
1/3 of the cycle
In order for a solid-state, semi conductor to conduct current, a _____ Change must be applied to the P side of the P-N Junction
Positive
In a rectifier,_____ flows with the direction of the arrow
Current
Which digit indicates the direction of the current flow
Middle
1 A= _____mA
1000
1 V= ______kV
.001
