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principles - grol

48 questions

QuestionAnswer
The product of the readings of an ac meter and ac ammeter is called: Apparent power
What is the basic unit of electrical power? Watts
What is the term to express the amount of electrical energy stored in an electrostatic field? Joules
What device is used to store electrical energy in an electrostatic field? Capacitor
What formula would determine the inductive reactance of a coil if frequency and coil inductance is known? XL = 2 (3.14) fl
What is the term for the out of phase power associated with inductors and capacitors? Reactive power
What determines the strength of the magnetic field around A conductor? The amount of current
What will produce a magnetic field? A current flowing through a conductor
When induced currents produce expanding magnetic fields around conductors in a direction That opposes the orignal magnetic field, this known as: lenz's law
The opposition To the creation of magnetic lines of force in a magnetic circuit is known as: reluctance
What is meant by the term "back EMF" ? A voltage that opposes the applied EMF
Permeability is defined as: the ratio of magnetic flux Density in a substance to the magnetizing force that produces it.
What metal is usually employed as a sacrifical anode for corrosion control purposes? Zinc bar
What is the relative dielectric constant for air? 1
Which metal object May be least affected by galvanic corrosion when submerged in seawater? Stainless steel propeller shaft
Skin effect is the phenomenon where: RF current flows in a thin layer of the conductor, closer to the surface, as frequency increases.
Corrosion resulting from electric current flow between dissimilar metals is called: Galvanic Corrosion
Which of these will be most useful for insulation at UHF frequencies? Mica
What formula would calculate the total inductance of inductors in series? Lt= l1+l2+l3...ln
Good conductors with minimum resistance have what type of electrons? Many free electrons
Which of the 4 groups of metals listed below are the best low-resistence conductors? Gold, silver, and copper
What is the purpose of a bypass capacitor? It removes alternating current providing a low impedance path to ground.
How would you calculate the total capacitance of three capacitors in parallel ? Ct=c1+c2+c3
How might you reduce the inductance of an antenna coil? Reduce the number of turns
What are the two most commonly used specifications for a junction diode? Maximum forward current and piv (peak inverse voltage)
What are the limits the maximum forward current of a Junction diode? The junction temperature
MOSFETs aee manufactured with THIS protective device built into their gate to protect the device from static charge and excessive voltages: zener diode
What are the two basic types of junction field effects transistors? N-channel and p-channel
A common emitter amplifier has: More voltage gain than a common collector
How does the input impedance of a field-effect transistor compare with that of a biopolar transistor? A FET has high input impedance ; a bipolar transistor has low input impedance.
An ac ammeter indicates: effective (rms) values of current.
By what factor must the voltage of an ac circuit , as indicated on the scale of an ac voltmeter, be multiplied to the peak voltage value? 1.414
What is the rms voltage at a common household electric power outlet? 117-v ac
What is the easiest voltage amplitude to a measure by viewing a pure sine wave signal on an oscilloscope? Peak to peak
By what factor must voltage measured in an ac circuit, as indicated on the scale of am ac voltmeter, be multiplied to obtain the average voltage value? 0.9
What is the peak voltage at a common household electrical outlet? 165.5 volts
What is a sine wave ? A wave whose amplitude at any given instant can be represented by the projection of a point on a wheel rotating uniform speed.
How many degrees are there in one complete sine wave cycle? 360°
What type of wave is made up of sine waves of the fundamental frequency and all odd harmonics? Square
what is the description of a square wave? A wave that abruptly changes back and forth between two voltage levels and stays at these levels for equal amount of time.
What type of wave is made up of sine waves at the fundamental frequency and all the harmonics? Sawtooth wave
What type of wave is characterized by a rise time significantly faster than the fall time (or vice versa)? Sawtooth wave
What is the term used to identify an ac voltage that would cause the same heating in a resistor as a corresponding value of dc voltage? Root mean square (rms)
What happens to reactive power in a circuit that has both inductors and capacitors? It alternates between magnetic and electric fields and is not dissipate.
Halving the cross-sectional area of a conductor will: double the resistance
Which of the following groups is correct for listing common materials in order of decending conductivity? Silver, copper, aluminum, iron, lead
How do you compute true power (power dissipated in the circuit) in a circuit where ac voltage and current are out of phase? Multiply apparent power times power factor .
Assuming a power source to have a fixed value of internal resistance, maximum power will be transferred to the load when: the load impedance equals the internal impedance of the source
Created by: pookee888
 

 



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