[D2L] Midterm Flashcards
What is Voltage?
A difference in charge between 2 points
Common temporary magnets we use in HVAC are…
Contactors
When all magnetic moments align, what is produced?
Magnetic Domain
With the left hand rule, grabbing the conductor with your left hand what do your fingers wrapping around it represent?
Direction of magnetic force
What is the basic principle of a transformer?
Mutual Induction
How is self induction created?
EMF traveling in the opposite direction due to Impedance
How many current paths are there in a series circuit?
one
Thermocouples use heat to generate Electricity?
True
What is static electricity?
the buildup of electrical charge in an isolated object
How many electrons in a coulomb
6.28 x 10 exponent 18
What is the symbol for electrical Charge?
Q
If an atom gains free electrons it becomes a
Negative Ion
When a car battery is dead
The charge is equalized
What amount of current is enough to kill a person?
100 to 200 mA
What is Applied voltage?
The Source voltage
What is voltage drop?
a reduction in voltage due to an increase in current
Which of the following is one way of stating Kirchhoff’s Voltage Law?
The algebraic sum of all voltages in a closed circuit is zero
Switches are devices that consume electricity while performing an action
False, they are loads
?What is Electromotive Force?
The energy used to move electrons away from atoms
What is the purpose of a lockout system while working on electrical systems?
To prevent shocks and the accidental start-up of the equipment being serviced.
What is electromagnetism?
The interaction of the forces that electric fields and magnetic fields create
How is alternating current generated?
By spinning a coil of wire 120 times per second.
When any force squeezes a crystals made from bone, wood, metal or minerals the material compresses and produces electricity, this is called…
Piezoelectricity
Which of the following is NOT considered part of electrical PPE for the RACM trade?
a) class 0 insulated gloves
b) long sleeve polyester shirt
c) multimeter
d) safety glasses
long sleeve polyester shirt
what is the FIRST thing that must be done if an electrical shock occurs?
remove the victim
Kirchhoff’s Current Law states that in an electrical circuit, the sum of the currents entering a junction must equal the sum of the currents leaving the junction
T or F
True
when illuminated, an incandescent light bulb will have a magnetic field close to the filament (glowing coil)?
True
By winding a wire into a coil, an electromagnet with poles will be produced when current is passed through the wire?
True
increasing the flow of current through a coil will..
increase the strength of the magnetic field
the number of lines of magnetic flux may be increased by adding an iron core in the middle.
True
A Megohmmeter (Megger) produces a _____ voltage output
High
ferromagnetic materials, like iron, allow magnetic flux to pass through them easily because they have a high
permeability
a material that does not allow easy passage of magnetic flux is said to have a high
reluctance
the emf that is induced in a circuit by electromagnetism, is proportional to the rate of change of flux linkage. this statement could be used to summarize?
faraday’s law
if the direction of current flow is reversed through a coil, the resulting magnetic field will..?
reverse direction
a DC transformer is widely used to convert a dangerous high voltage power source to a safer and more usable control voltage?
False, Transformer is always AC
passing a conductor in parallel to lines of flux will induce a current of electromotive force?
T or F
False
an alternator converts…………………, into…………………… energy
mechanical, electrical
in order to provide a useful low voltage control signal, a transformers primary and secondary coils should be in contact at each end of their conductors?
False, they should be isolated from each other
