FCC ELEMENT 3 EXAM REPORTED
QUESTIONS WITH CORRECT
ANSWERS
3-12B2 | At 150 degrees, what is the amplitude of a sine-wave having a peak value of 5
volts? - Answer-C. +2.5 volts.
3-12B3 | At 240 degrees, what is the amplitude of a sine-wave having a peak value of 5
volts? - Answer-A. -4.3 volts.
3-12B4 | What is the equivalent to the root-mean-square value of an AC voltage? -
Answer-D. The DC voltage causing the same heating in a given resistor as the RMS AC
voltage of the same value.
3-12B5 | What is the RMS value of a 340-volt peak-to-peak pure sine wave? - Answer-
C. 120 volts AC.
3-12B6 | Determine the phase relationship between the two signals shown in Figure
3B3. - Answer-B. B is lagging A by 90 degrees.
3-13B1 | What does the power factor equal in an R-L circuit having a 60 degree phase
angle between the voltage and the current? - Answer-C. 0.5
3-13B2 | If a resistance to which a constant voltage is applied is halved, what power
dissipation will result? - Answer-A. Double.
3-13B3 | 746 watts, corresponding to the lifting of 550 pounds at the rate of one-foot-
per-second, is the equivalent of how much horsepower? - Answer-D. One horsepower.
3-13B4 | In a circuit where the AC voltage and current are out of phase, how can the
true power be determined? - Answer-A. By multiplying the apparent power times the
power factor.
3-13B5 | What does the power factor equal in an R-L circuit having a 45 degree phase
angle between the voltage and the current? - Answer-D. 0.707
3-13B6 | What does the power factor equal in an R-L circuit having a 30 degree phase
angle between the voltage and the current? - Answer-B. 0.866
3-14B1 | What is the term for the time required for the capacitor in an RC circuit to be
charged to 63.2% of the supply voltage? - Answer-B. One time constant.
, 3-14B2 | What is the meaning of the term "time constant of an RC circuit"? The time
required to charge the capacitor in the circuit to: - Answer-D. 63.2% of the supply
voltage.
3-14B3 | What is the term for the time required for the current in an RL circuit to build up
to 63.2% of the maximum value? - Answer-A. One time constant.
3-14B4 | What is the meaning of the term "time constant of an RL circuit"? The time
required for the: - Answer-C. Current in the circuit to build up to 63.2% of the maximum
value.
3-14B5 | After two time constants, the capacitor in an RC circuit is charged to what
percentage of the supply voltage? - Answer-C. 86.5 %
3-14B6 | After two time constants, the capacitor in an RC circuit is discharged to what
percentage of the starting voltage? - Answer-B. 13.5 %
3-15B1 | What is the time constant of a circuit having two 220-microfarad capacitors and
two 1-megohm resistors all in parallel? - Answer-D. 220 seconds.
3-15B2 | What is the time constant of a circuit having two 100-microfarad capacitors and
two 470-kilohm resistors all in series? - Answer-B. 47 seconds
3-15B3 | What is the time constant of a circuit having a 100-microfarad capacitor and a
470-kilohm resistor in series? - Answer-C. 47 seconds.
3-15B4 | What is the time constant of a circuit having a 220-microfarad capacitor and a
1-megohm resistor in parallel? - Answer-A. 220 seconds.
3-15B5 | What is the time constant of a circuit having two 100-microfarad capacitors and
two 470-kilohm resistors all in parallel? - Answer-B. 47 seconds.
3-15B6 | What is the time constant of a circuit having two 220-microfarad capacitors and
two 1-megohm resistors all in series? - Answer-A. 220 seconds.
3-16B1 | What is the impedance of a network composed of a 0.1-microhenry inductor in
series with a 20-ohm resistor, at 30 MHz? Specify your answer in rectangular
coordinates. - Answer-C. 20 +j19
3-16B2 | In rectangular coordinates, what is the impedance of a network composed of a
0.1-microhenry inductor in series with a 30-ohm resistor, at 5 MHz? - Answer-D. 30 +j3
3-16B3 | In rectangular coordinates, what is the impedance of a network composed of a
10-microhenry inductor in series with a 40-ohm resistor, at 500 MHz? - Answer-A. 40
+j31400
QUESTIONS WITH CORRECT
ANSWERS
3-12B2 | At 150 degrees, what is the amplitude of a sine-wave having a peak value of 5
volts? - Answer-C. +2.5 volts.
3-12B3 | At 240 degrees, what is the amplitude of a sine-wave having a peak value of 5
volts? - Answer-A. -4.3 volts.
3-12B4 | What is the equivalent to the root-mean-square value of an AC voltage? -
Answer-D. The DC voltage causing the same heating in a given resistor as the RMS AC
voltage of the same value.
3-12B5 | What is the RMS value of a 340-volt peak-to-peak pure sine wave? - Answer-
C. 120 volts AC.
3-12B6 | Determine the phase relationship between the two signals shown in Figure
3B3. - Answer-B. B is lagging A by 90 degrees.
3-13B1 | What does the power factor equal in an R-L circuit having a 60 degree phase
angle between the voltage and the current? - Answer-C. 0.5
3-13B2 | If a resistance to which a constant voltage is applied is halved, what power
dissipation will result? - Answer-A. Double.
3-13B3 | 746 watts, corresponding to the lifting of 550 pounds at the rate of one-foot-
per-second, is the equivalent of how much horsepower? - Answer-D. One horsepower.
3-13B4 | In a circuit where the AC voltage and current are out of phase, how can the
true power be determined? - Answer-A. By multiplying the apparent power times the
power factor.
3-13B5 | What does the power factor equal in an R-L circuit having a 45 degree phase
angle between the voltage and the current? - Answer-D. 0.707
3-13B6 | What does the power factor equal in an R-L circuit having a 30 degree phase
angle between the voltage and the current? - Answer-B. 0.866
3-14B1 | What is the term for the time required for the capacitor in an RC circuit to be
charged to 63.2% of the supply voltage? - Answer-B. One time constant.
, 3-14B2 | What is the meaning of the term "time constant of an RC circuit"? The time
required to charge the capacitor in the circuit to: - Answer-D. 63.2% of the supply
voltage.
3-14B3 | What is the term for the time required for the current in an RL circuit to build up
to 63.2% of the maximum value? - Answer-A. One time constant.
3-14B4 | What is the meaning of the term "time constant of an RL circuit"? The time
required for the: - Answer-C. Current in the circuit to build up to 63.2% of the maximum
value.
3-14B5 | After two time constants, the capacitor in an RC circuit is charged to what
percentage of the supply voltage? - Answer-C. 86.5 %
3-14B6 | After two time constants, the capacitor in an RC circuit is discharged to what
percentage of the starting voltage? - Answer-B. 13.5 %
3-15B1 | What is the time constant of a circuit having two 220-microfarad capacitors and
two 1-megohm resistors all in parallel? - Answer-D. 220 seconds.
3-15B2 | What is the time constant of a circuit having two 100-microfarad capacitors and
two 470-kilohm resistors all in series? - Answer-B. 47 seconds
3-15B3 | What is the time constant of a circuit having a 100-microfarad capacitor and a
470-kilohm resistor in series? - Answer-C. 47 seconds.
3-15B4 | What is the time constant of a circuit having a 220-microfarad capacitor and a
1-megohm resistor in parallel? - Answer-A. 220 seconds.
3-15B5 | What is the time constant of a circuit having two 100-microfarad capacitors and
two 470-kilohm resistors all in parallel? - Answer-B. 47 seconds.
3-15B6 | What is the time constant of a circuit having two 220-microfarad capacitors and
two 1-megohm resistors all in series? - Answer-A. 220 seconds.
3-16B1 | What is the impedance of a network composed of a 0.1-microhenry inductor in
series with a 20-ohm resistor, at 30 MHz? Specify your answer in rectangular
coordinates. - Answer-C. 20 +j19
3-16B2 | In rectangular coordinates, what is the impedance of a network composed of a
0.1-microhenry inductor in series with a 30-ohm resistor, at 5 MHz? - Answer-D. 30 +j3
3-16B3 | In rectangular coordinates, what is the impedance of a network composed of a
10-microhenry inductor in series with a 40-ohm resistor, at 500 MHz? - Answer-A. 40
+j31400
