CHAPTER 28 POWER POINT Flashcards
a force that acts at a distance and is caused by a magnetic field.
MAGNETISM
a device that attracts iron and steel because of the molecular alignment of its material•May be permanent or temporary
Magnet
the invisible lines of force that make up the magnetic field
Magnetic flux
Magnetic Flux (force) lines travel in same direction
Unlike magnetic poles
________ poles attract
Unlike magnetic poles
______poles repel
Like magnetic poles
Magnetic Flux (force) Lines travel in opposite directions.
Like Magnetic poles
produced any time electricity passes through a conductor.
Magnetic field
the magnetic field produced when electricity passes through a conductor. Is a temporary magnetic force, because the magnetic field is present only as long as current flows.
Electromagnetism
On standard ____ (cycle) power frequencies, the current passes the zero point ____ times per second.
60 Hz
120
a device that converts electrical energy into a linear, mechanical force.
Solenoid
A solenoid uses __________.
Electromagnetic force
Provide a liner, mechanical force when electricity is applied to the coil.
Solenoid
A solenoid is utilized in applications that use short strokes at ______.
low force
In a solenoid, the ______ is removed from the coil by a spring.
iron core
In a solenoid a magnetic field produced around coil when current flow through _____.
Windings
In a solenoid a magnetic force draws ____ into a coil.
Iron core
In a solenoid where is the drum mounted?
on the motor shaft
A solenoid is used to open what when it is energized?
brake
What is used to close the brake when Solenoid is de-energized?
spring
Solenoids develop linear force in applications that use _______ at low force.
short strokes
Solenoids common electrical applications are to:
•Control the flow of water or gas in: Washing machines, Dishwashers, Dryers, Control door locks, Stamp information, Dispense coins
an electric device that uses electromagnetism to change voltage from one level to another or to isolate one voltage from another.
Transformer
Primarily used to step up or step down voltage.
Transformers
A transformer consist of two or more coils of insulated wire wound on a __________.
laminated steel core
coil to which the voltage is connected on the input side.
Primary coil
coil in which the voltage is induced on the output side
Secondary coil:
when the magnetic flux lines from one expanding and contracting magnetic field cut the windings of a second coil, a voltage is induced in the second coil.
The principle of electromagnetic mutual induction
are materials that can be magnetized easily.
Ferromagnetic materials
are materials that cannot be magnetized easily.
Paramagnetic materials
are materials that cannot be magnetized under normal conditions.
Diamagnetic materials
In transformers to calculate the relationship between the number of turns and the voltage:
Ep/Es = Np/Ns
In a transformer ______ is connected to primary.
Supply voltage
In a transformer _____ connected to secondary.
loads
In a step-up transformer there are more turns of wire on the ______.
Secondary coil
In a step-up transformer Induced voltage is ____ than applied voltage.
Higher
In a step-down transformer ____ turns if wire on secondary coil.
fewer
In a step-down transformer induced voltage ___ than applied voltage.
lower