CFESA ELECTRICAL COMPREHENSIVE EXAM QUESTIONS
AND 100% VERIFIED ANSWERS RECENTLY UPDATED
300 QUESTIONS AND ANSWERS
1. What is Ohm's Law? Answer: Ohm's Law states that voltage (V) equals
current (I) multiplied by resistance (R). The formula is V = I × R.
2. What is the unit of measurement for electrical current? Answer: Amperes
(Amps or A).
3. What is the unit of measurement for electrical voltage? Answer: Volts
(V).
4. What is the unit of measurement for electrical resistance? Answer: Ohms
(Ω).
5. What is the unit of measurement for electrical power? Answer: Watts
(W).
6. How do you calculate electrical power? Answer: Power (P) = Voltage (V)
× Current (I), or P = V × I.
7. What is the difference between AC and DC current? Answer: AC
(Alternating Current) changes direction periodically, while DC (Direct Current)
flows in one direction only.
8. What is the standard frequency of AC power in North America? Answer:
60 Hz (Hertz).
9. What is the standard frequency of AC power in most of Europe? Answer:
50 Hz (Hertz).
10. What is electrical conductance? Answer: Electrical conductance is the
ability of a material to conduct electric current, measured in siemens (S).
11. What is electrical impedance? Answer: Impedance is the total opposition
to current flow in an AC circuit, combining resistance and reactance.
,12. What is the difference between resistance and reactance? Answer:
Resistance opposes current flow in both AC and DC circuits, while reactance
only opposes AC current flow.
13. What is RMS voltage? Answer: Root Mean Square voltage is the effective
AC voltage that produces the same heating effect as an equivalent DC voltage.
14. What is peak voltage? Answer: Peak voltage is the maximum
instantaneous voltage reached in an AC waveform.
15. What is the relationship between peak and RMS voltage? Answer: RMS
voltage = Peak voltage ÷ √2 (approximately Peak voltage × 0.707).
16. What is a kilowatt-hour (kWh)? Answer: A kilowatt-hour is a unit of
energy equal to 1000 watts used for one hour.
17. What is power factor? Answer: Power factor is the ratio of real power to
apparent power in an AC circuit, expressed as a decimal or percentage.
18. What causes poor power factor? Answer: Inductive loads such as motors,
transformers, and fluorescent lights cause poor (lagging) power factor.
19. What is the formula for calculating three-phase power? Answer: P = √3
× V × I × cos(φ), where φ is the phase angle.
20. What is the difference between line voltage and phase voltage in a
three-phase system? Answer: In a wye system, line voltage = √3 × phase
voltage. In a delta system, line voltage = phase voltage.
21. What is an electrical short circuit? Answer: A short circuit occurs when
current takes an unintended path with very low resistance, bypassing the normal
load.
22. What is an open circuit? Answer: An open circuit is a break in the
electrical path that prevents current flow.
23. What is a ground fault? Answer: A ground fault occurs when electrical
current flows to ground through an unintended path.
24. What is electrical inductance? Answer: Inductance is the property of a
conductor that opposes changes in current flow, measured in henries (H).
25. What is electrical capacitance? Answer: Capacitance is the ability to store
electrical charge, measured in farads (F).
, 26. What is the time constant in an RC circuit? Answer: The time constant
(τ) = Resistance (R) × Capacitance (C), representing the time for voltage to
reach 63.2% of its final value.
27. What is the time constant in an RL circuit? Answer: The time constant
(τ) = Inductance (L) ÷ Resistance (R).
28. What is mutual inductance? Answer: Mutual inductance is the ability of
one coil to induce voltage in another nearby coil.
29. What is self-inductance? Answer: Self-inductance is the ability of a coil to
induce voltage in itself when current changes.
30. What is electromagnetic induction? Answer: Electromagnetic induction is
the process of generating voltage by changing magnetic flux through a
conductor.
31. What is Lenz's Law? Answer: Lenz's Law states that induced current flows
in a direction to oppose the change that created it.
32. What is Kirchhoff's Current Law (KCL)? Answer: KCL states that the
sum of currents entering a node equals the sum of currents leaving that node.
33. What is Kirchhoff's Voltage Law (KVL)? Answer: KVL states that the
sum of voltage drops around any closed loop equals the applied voltage.
34. What is the difference between series and parallel circuits? Answer:
Series circuits have one path for current flow; parallel circuits have multiple
paths for current flow.
35. How does current behave in a series circuit? Answer: Current is the same
at all points in a series circuit.
36. How does voltage behave in a series circuit? Answer: Voltage divides
proportionally across components based on their resistance values.
37. How does current behave in a parallel circuit? Answer: Current divides
among parallel branches inversely proportional to their resistance.
38. How does voltage behave in a parallel circuit? Answer: Voltage is the
same across all parallel branches.
39. What is the total resistance of resistors in series? Answer: RT = R1 + R2
+ R3 + ... (sum of all resistances).
AND 100% VERIFIED ANSWERS RECENTLY UPDATED
300 QUESTIONS AND ANSWERS
1. What is Ohm's Law? Answer: Ohm's Law states that voltage (V) equals
current (I) multiplied by resistance (R). The formula is V = I × R.
2. What is the unit of measurement for electrical current? Answer: Amperes
(Amps or A).
3. What is the unit of measurement for electrical voltage? Answer: Volts
(V).
4. What is the unit of measurement for electrical resistance? Answer: Ohms
(Ω).
5. What is the unit of measurement for electrical power? Answer: Watts
(W).
6. How do you calculate electrical power? Answer: Power (P) = Voltage (V)
× Current (I), or P = V × I.
7. What is the difference between AC and DC current? Answer: AC
(Alternating Current) changes direction periodically, while DC (Direct Current)
flows in one direction only.
8. What is the standard frequency of AC power in North America? Answer:
60 Hz (Hertz).
9. What is the standard frequency of AC power in most of Europe? Answer:
50 Hz (Hertz).
10. What is electrical conductance? Answer: Electrical conductance is the
ability of a material to conduct electric current, measured in siemens (S).
11. What is electrical impedance? Answer: Impedance is the total opposition
to current flow in an AC circuit, combining resistance and reactance.
,12. What is the difference between resistance and reactance? Answer:
Resistance opposes current flow in both AC and DC circuits, while reactance
only opposes AC current flow.
13. What is RMS voltage? Answer: Root Mean Square voltage is the effective
AC voltage that produces the same heating effect as an equivalent DC voltage.
14. What is peak voltage? Answer: Peak voltage is the maximum
instantaneous voltage reached in an AC waveform.
15. What is the relationship between peak and RMS voltage? Answer: RMS
voltage = Peak voltage ÷ √2 (approximately Peak voltage × 0.707).
16. What is a kilowatt-hour (kWh)? Answer: A kilowatt-hour is a unit of
energy equal to 1000 watts used for one hour.
17. What is power factor? Answer: Power factor is the ratio of real power to
apparent power in an AC circuit, expressed as a decimal or percentage.
18. What causes poor power factor? Answer: Inductive loads such as motors,
transformers, and fluorescent lights cause poor (lagging) power factor.
19. What is the formula for calculating three-phase power? Answer: P = √3
× V × I × cos(φ), where φ is the phase angle.
20. What is the difference between line voltage and phase voltage in a
three-phase system? Answer: In a wye system, line voltage = √3 × phase
voltage. In a delta system, line voltage = phase voltage.
21. What is an electrical short circuit? Answer: A short circuit occurs when
current takes an unintended path with very low resistance, bypassing the normal
load.
22. What is an open circuit? Answer: An open circuit is a break in the
electrical path that prevents current flow.
23. What is a ground fault? Answer: A ground fault occurs when electrical
current flows to ground through an unintended path.
24. What is electrical inductance? Answer: Inductance is the property of a
conductor that opposes changes in current flow, measured in henries (H).
25. What is electrical capacitance? Answer: Capacitance is the ability to store
electrical charge, measured in farads (F).
, 26. What is the time constant in an RC circuit? Answer: The time constant
(τ) = Resistance (R) × Capacitance (C), representing the time for voltage to
reach 63.2% of its final value.
27. What is the time constant in an RL circuit? Answer: The time constant
(τ) = Inductance (L) ÷ Resistance (R).
28. What is mutual inductance? Answer: Mutual inductance is the ability of
one coil to induce voltage in another nearby coil.
29. What is self-inductance? Answer: Self-inductance is the ability of a coil to
induce voltage in itself when current changes.
30. What is electromagnetic induction? Answer: Electromagnetic induction is
the process of generating voltage by changing magnetic flux through a
conductor.
31. What is Lenz's Law? Answer: Lenz's Law states that induced current flows
in a direction to oppose the change that created it.
32. What is Kirchhoff's Current Law (KCL)? Answer: KCL states that the
sum of currents entering a node equals the sum of currents leaving that node.
33. What is Kirchhoff's Voltage Law (KVL)? Answer: KVL states that the
sum of voltage drops around any closed loop equals the applied voltage.
34. What is the difference between series and parallel circuits? Answer:
Series circuits have one path for current flow; parallel circuits have multiple
paths for current flow.
35. How does current behave in a series circuit? Answer: Current is the same
at all points in a series circuit.
36. How does voltage behave in a series circuit? Answer: Voltage divides
proportionally across components based on their resistance values.
37. How does current behave in a parallel circuit? Answer: Current divides
among parallel branches inversely proportional to their resistance.
38. How does voltage behave in a parallel circuit? Answer: Voltage is the
same across all parallel branches.
39. What is the total resistance of resistors in series? Answer: RT = R1 + R2
+ R3 + ... (sum of all resistances).
