Electrical principles Flashcards
definition of DC
current that flows in one direction only
definition of AC
is current that periodically changes direction
definition of electric current
is rate of movement of charge measured in amperes
definition of EMF
is force that causes current to flow measured in volts
definition of potential difference
the change in electrical potential between two points in a circuit
definition of resistance
is the opposition to current flow that a resistor exerts in a circuit
definition of absolute potential
is the voltage at a point in a circuit with reference to earth
definition of a conductor
is a material with low resistance that allows current flow
definition of an insulator
is a material with high resistance that dose not allow current to flow
definition of a semiconductor
is a material that is neither a good conductor or insulator but can be made to exhibit some great properties
definition of an ammeter
is an instrument that has low resistance and is used to measure current. it is placed in series with the load
definition of a voltmeter
is an instrument that is used to measure power
definition of ohmmeter
is an instrument that is used to measure resistance. is is placed in parallel with the resistor after is has been removed from the circuit
definition of a wattmeter
is an instrument that is used to measure power
definition of mit420 or bridge megger
are instruments that are used to measure both continuity and insulation resistance
definition of tachometer or stroboscope
is an instrument that is used to measure rotational speed
definition of ohms law
the current flowing in a circuit is directly proportional to the voltage applied inversely proportional to the resistance as long as the temp remains constant
factors that effect resistance
- type of material
- length
- cross sectional area
what are kirchoffs laws
current law
voltage law
define kirchoffs current law
the amount of current flowing towards a junction or node in a circuit is equal to the amount flowing away
define kirchoffs voltage law
the sum of the voltage drops around a closed loop in a circuit is equal to the EMFs acting in a closed loop
definition of a potentiometer
uses three terminals and is used for voltage control
definition of a rheostat
uses two terminals and is used for current control
definition of a capacitor
is a deceive that is used to temporally store electrical energy or charge. two plates that are separated by a dielectric
factors that effect capacitance
- number of turns of wire
- the cross sectional area of the coil
- the presence of a magnetic core
- the way the turns are arranged