3.13 & 3.14 - AC Theory and LCR
Circuits Exam 2025 With 100% Correct
Answers
What is a cycle (AC wave)? - CORRECT ANSWER✔✔A cycle is one complete sequence of voltage
or current change from zero through a positive peak, back to zero, through a negative peak and
back to zero again.
What is an alternation (AC wave)? - CORRECT ANSWER✔✔One half of an AC cycle, in which the
voltage or current rises or falls from zero to a peak and back to zero again.
What is the frequency of AC? - CORRECT ANSWER✔✔The number of cycles completed in one
second. Frequency is expressed in hertz (Hz), with one hertz equal to one cycle per second. If
the loop makes one complete revolution each second, the generator produces one complete
cycle of AC during each second (1 Hz).
What is the period of a sine wave? - CORRECT ANSWER✔✔The time required to complete one
cycle of a waveform
What effect does an increase in the number of poles cause to the number of cycles completed
in a revolution? - CORRECT ANSWER✔✔Increases it,
A two-pole generator completes one cycle per revolution and a four-pole generator completes
two cycles per revolution
What is the peak voltage in a sine wave? - CORRECT ANSWER✔✔The peak value of a sine wave
occurs twice each cycle: once at the positive maximum value and once at the negative
maximum value.
, What is the peak-to-peak voltage or current? - CORRECT ANSWER✔✔The magnitude of the
voltage or current between the peak positive and peak negative values.
What is the instantaneous voltage or current? - CORRECT ANSWER✔✔The instantaneous value
of voltage or current is the value at any time on the sine wave. It can be anywhere from zero to
peak value.
What is the formula to calculate instantaneous voltage or current? - CORRECT ANSWER✔✔The
instantaneous value of the sine wave is found by the following formula:
VINST = VPK × sinØ
Ø is the angle of rotation of the cycle.
What is Root Mean Square (RMS)? - CORRECT ANSWER✔✔The 'amount of AC power that
produces the same heating effect as an equivalent DC power'.
It is the square root of the mean, or average, value of the squared function of the instantaneous
values.
For a sine wave, the RMS value is 0.707 times the peak value. Voltmeters measure in average
but indicate AC as RMS
RMS voltage or current = _____________ of peak value - CORRECT ANSWER✔✔0.707
What is the average value of an alternating current or voltage? - CORRECT ANSWER✔✔It is the
average of all the instantaneous values during one alternation.
Circuits Exam 2025 With 100% Correct
Answers
What is a cycle (AC wave)? - CORRECT ANSWER✔✔A cycle is one complete sequence of voltage
or current change from zero through a positive peak, back to zero, through a negative peak and
back to zero again.
What is an alternation (AC wave)? - CORRECT ANSWER✔✔One half of an AC cycle, in which the
voltage or current rises or falls from zero to a peak and back to zero again.
What is the frequency of AC? - CORRECT ANSWER✔✔The number of cycles completed in one
second. Frequency is expressed in hertz (Hz), with one hertz equal to one cycle per second. If
the loop makes one complete revolution each second, the generator produces one complete
cycle of AC during each second (1 Hz).
What is the period of a sine wave? - CORRECT ANSWER✔✔The time required to complete one
cycle of a waveform
What effect does an increase in the number of poles cause to the number of cycles completed
in a revolution? - CORRECT ANSWER✔✔Increases it,
A two-pole generator completes one cycle per revolution and a four-pole generator completes
two cycles per revolution
What is the peak voltage in a sine wave? - CORRECT ANSWER✔✔The peak value of a sine wave
occurs twice each cycle: once at the positive maximum value and once at the negative
maximum value.
, What is the peak-to-peak voltage or current? - CORRECT ANSWER✔✔The magnitude of the
voltage or current between the peak positive and peak negative values.
What is the instantaneous voltage or current? - CORRECT ANSWER✔✔The instantaneous value
of voltage or current is the value at any time on the sine wave. It can be anywhere from zero to
peak value.
What is the formula to calculate instantaneous voltage or current? - CORRECT ANSWER✔✔The
instantaneous value of the sine wave is found by the following formula:
VINST = VPK × sinØ
Ø is the angle of rotation of the cycle.
What is Root Mean Square (RMS)? - CORRECT ANSWER✔✔The 'amount of AC power that
produces the same heating effect as an equivalent DC power'.
It is the square root of the mean, or average, value of the squared function of the instantaneous
values.
For a sine wave, the RMS value is 0.707 times the peak value. Voltmeters measure in average
but indicate AC as RMS
RMS voltage or current = _____________ of peak value - CORRECT ANSWER✔✔0.707
What is the average value of an alternating current or voltage? - CORRECT ANSWER✔✔It is the
average of all the instantaneous values during one alternation.
