EM2 Flashcards
A_______oscilloscope has two vertical inputs
Dual Trace
An Ideal transformer what is the relatiosnship between the output power and the input power?
Power out would be equal to power in.
The core with the highest permeability is?
soft iron
What is the one hand rule when working on electronic equipment ?
keeping one hand free will minimize the possibility of creating a low resistance path to ground through your body/
What do you adjust on an osciliscope to determine the number of waves displayed?
Time per division
_____is the term for the combination of reactance and resistance that restrict the flow of alternating current>
impendence
if you use a x10 probe instead of direct x1 probe on an oscilloscope, what effect does it have on the circuit test?
it decreases circuit loading
which of the following function is not a common use for an inductor?
boosting low level signals
What are the main functions of a transformer ?
isolation/coupling step up/down
Which of the following function is not the common use of a capacitor ?
Radiating a signal
______is known as the time it takes to charge a capacitor to 63 percent.
time constant
the positive peak of a sine wave corresponds to
90 degrees
what factors effect the velocity propagation factor of a coax cable
dielectric constant and permeability
One megahertz is defined as one_____per second
million cycles
the ammeter function on a multimeeter is used to measure which of the following ?
current
Which of the following controls adjust the amplitude size of the waveforms on the screen?
vertical sensitivity
what has a 50 ohms impendence
RG 58
1x10with a little 9 next to the 10
Giga
what voltage is applied across each branch in a parallel RC circuit
total circuit voltage
what is the period of a one hertz waveform?
1 second
______is term used to refer to an inductor
coil
What is the time it takes to produce a cycle of a waveform?
period
For low resistance measurement, test leads resistance should be compensated by?
shortening the test leads , finding their resistance and then subtracting that from the measurement.
Which widening of a transformer is normally connected to the output voltage?
secondary
inductance varies as the _____of the number of turns
square
unused leads in a transformer should be
insulated from each other
When an AC voltage source is supplied across a capacitor the current flow within the circuit will be at a minimum when the sine voltage is at its________
Peak value
Unless re identified with electrical tape the color ____should not be used for the hot wire in a standard 120 v wall outlet circuit.
white
The four types of transformer are
power, rf and audio, isolation
In a resonant circuit, capacitance equals inductance
false
self inductance is the process by which the changing magnetic field around a conductor induces positive electromotive in the conductor itself
false
In an iron core or transformer what is the purpose of insulated lamination?
reduces power wasting edgy currents
The voltage rating of a capacitor _______
relates to the maximum voltage that should be applied to it
Even if not connected to a circuit , should a large capacitor be considered dangerous?
all large capacitors are potentially dangerous
what is the phase relationship in a resistive capacitive circuit where the vector line relationship two lines perpendicular to each other?
90 degree difference
in a _______circuit voltage leads current
inductive
A burning microwave oven is the example of a _____fire
class c
In a capacitive circuit what is the phase relationship of voltage and current ?
current leads
Frequency has what unit of measurement?
hertz
On an osciliscope which control do you use to adgjust the top to a bottom location of a waveform displayed on the screen?
vertical position
An alternating current is a sinusoidal with a positive and negative alternation t/f?
true
In a parallel rc circuit the phase relationship between voltage and current is?
90 degrees in the capacitive branch and in phase of the restrictive branch
When measuring current the meter should always be?
connected in series with the load
Balanced signal wiring is done
to reduce the circuits vulnerability to external interference
the impendence for rg58 coax cable is
50 ohms
as the distance between the plates of a capacitor decreases the capacitance value ______
increases
a capacitor is made up of _____
two plates seperated by a dielectric
when the current goes positive at the same time that the voltage producing it goes negative the current is said to be______
out of phase
current leads or lags voltage when an ac voltage is applied across a capacitor
leads
The y axis’s of an oscilloscope is used to measure
amplitude
What is the fourth harmonic of 15 khz?
60KHZ
The inductive reactance ______an inductor if the frequency of the applied voltage is doubled .
is twice the previous value
a resonant circuit with a narrow bandwidth is considered to have a_______
high q
Which of the following events would cause an inductive flyback transient to occur
switch contacts in a highly inductive circuit open
The capacitance reaction will________when the frequency of an applied voltage is increased.
decrease
______is dependant on material and dimension used in the design of each type of coax cables
characteristic impendance
when a current level of 0.1 amps from arm to arm in the average adult it would likely result in _____
a death
What is the unit of measure for inductors?
henry
A sinewave has which of the following characteristics ?
sharp rise and fall times in relations to its period
