CFESA ELECTRICAL TEST
Questions & Answers| Latest Update
Covering: Basic Electrical Theory • AC/DC Fundamentals • Single & Three-Phase Power •
Transformers • Motors • Controls (Relays, Contactors, Solenoids) • Switches, Timers &
Thermostats • Heating Elements • Overcurrent Protection • Test Instruments & Safety
,1. What is the formula for Ohm's Law used to find voltage?
A) E = I ÷ R
B) E = I × R
C) E = R ÷ I
D) E = I²R
Answer: B
Rationale: Ohm's Law relates voltage, current, and resistance. Voltage equals current
multiplied by resistance (E = I × R), which is derived from the base relationship I = E ÷
R.
2. According to Ohm's Law, if resistance increases while voltage stays constant,
current will:
A) Increase
B) Decrease
C) Stay the same
D) Become zero
Answer: B
Rationale: Current is inversely proportional to resistance when voltage is held
constant (I = E ÷ R). As resistance goes up, current goes down.
3. What is the unit of electrical resistance?
A) Ampere
B) Ohm
C) Watt
D) Volt
Answer: B
Rationale: Resistance is measured in ohms, symbolized by the Greek letter omega (Ω),
named after Georg Ohm.
4. The formula for electrical power is:
A) P = E ÷ I
B) P = E × I
C) P = I ÷ E
D) P = E − I
Answer: B
, Rationale: Power in watts equals voltage multiplied by current (P = E × I). This is the
basic power formula used throughout electrical troubleshooting.
5. A circuit has 120V applied and draws 5A. What is the resistance?
A) 5 Ω
B) 24 Ω
C) 600 Ω
D) 0.04 Ω
Answer: B
Rationale: Using R = E ÷ I, 120V ÷ 5A = 24 ohms.
6. A 1,500W heating element operates at 120V. What current does it draw?
A) 12.5 A
B) 8 A
C) 18 A
D) 150 A
Answer: A
Rationale: Using I = P ÷ E, 1,500W ÷ 120V = 12.5 amps.
7. In a series circuit, total resistance equals:
A) The reciprocal sum of individual resistances
B) The sum of the individual resistances
C) The product divided by the sum of resistances
D) Only the largest resistor value
Answer: B
Rationale: In a series circuit, resistances add directly: R(total) = R1 + R2 + R3, since
current has only one path to follow through every resistor.
8. In a parallel circuit, total current equals:
A) The average of branch currents
B) The sum of the branch currents
C) Voltage divided by one branch's resistance only
D) Zero
Answer: B
Rationale: Total current in a parallel circuit is the sum of the current flowing through
each individual branch, since each branch offers its own path back to the source.
, 9. Which statement about parallel circuits is TRUE?
A) Voltage differs across each branch
B) Current is the same in every branch
C) Voltage is the same across each branch
D) Total resistance is greater than any single branch resistance
Answer: C
Rationale: Every branch of a parallel circuit is connected directly across the same two
points, so each branch sees the same applied voltage.
10. What happens to total resistance when additional resistors are added in parallel?
A) It increases
B) It decreases
C) It stays the same
D) It becomes infinite
Answer: B
Rationale: Adding parallel paths gives current more routes to flow, which always
lowers total circuit resistance below the value of the smallest branch resistor.
11. Which meter is used to measure current in a live circuit without breaking the
circuit open?
A) Ohmmeter
B) Clamp-on ammeter
C) Voltmeter
D) Megohmmeter
Answer: B
Rationale: A clamp-on ammeter senses the magnetic field around a single energized
conductor, allowing current measurement without disconnecting any wiring.
12. What does the term "continuity" refer to when testing a component?
A) The presence of voltage
B) An unbroken, complete path for current flow
C) Excess resistance in a circuit
D) A grounded condition
Answer: B
Questions & Answers| Latest Update
Covering: Basic Electrical Theory • AC/DC Fundamentals • Single & Three-Phase Power •
Transformers • Motors • Controls (Relays, Contactors, Solenoids) • Switches, Timers &
Thermostats • Heating Elements • Overcurrent Protection • Test Instruments & Safety
,1. What is the formula for Ohm's Law used to find voltage?
A) E = I ÷ R
B) E = I × R
C) E = R ÷ I
D) E = I²R
Answer: B
Rationale: Ohm's Law relates voltage, current, and resistance. Voltage equals current
multiplied by resistance (E = I × R), which is derived from the base relationship I = E ÷
R.
2. According to Ohm's Law, if resistance increases while voltage stays constant,
current will:
A) Increase
B) Decrease
C) Stay the same
D) Become zero
Answer: B
Rationale: Current is inversely proportional to resistance when voltage is held
constant (I = E ÷ R). As resistance goes up, current goes down.
3. What is the unit of electrical resistance?
A) Ampere
B) Ohm
C) Watt
D) Volt
Answer: B
Rationale: Resistance is measured in ohms, symbolized by the Greek letter omega (Ω),
named after Georg Ohm.
4. The formula for electrical power is:
A) P = E ÷ I
B) P = E × I
C) P = I ÷ E
D) P = E − I
Answer: B
, Rationale: Power in watts equals voltage multiplied by current (P = E × I). This is the
basic power formula used throughout electrical troubleshooting.
5. A circuit has 120V applied and draws 5A. What is the resistance?
A) 5 Ω
B) 24 Ω
C) 600 Ω
D) 0.04 Ω
Answer: B
Rationale: Using R = E ÷ I, 120V ÷ 5A = 24 ohms.
6. A 1,500W heating element operates at 120V. What current does it draw?
A) 12.5 A
B) 8 A
C) 18 A
D) 150 A
Answer: A
Rationale: Using I = P ÷ E, 1,500W ÷ 120V = 12.5 amps.
7. In a series circuit, total resistance equals:
A) The reciprocal sum of individual resistances
B) The sum of the individual resistances
C) The product divided by the sum of resistances
D) Only the largest resistor value
Answer: B
Rationale: In a series circuit, resistances add directly: R(total) = R1 + R2 + R3, since
current has only one path to follow through every resistor.
8. In a parallel circuit, total current equals:
A) The average of branch currents
B) The sum of the branch currents
C) Voltage divided by one branch's resistance only
D) Zero
Answer: B
Rationale: Total current in a parallel circuit is the sum of the current flowing through
each individual branch, since each branch offers its own path back to the source.
, 9. Which statement about parallel circuits is TRUE?
A) Voltage differs across each branch
B) Current is the same in every branch
C) Voltage is the same across each branch
D) Total resistance is greater than any single branch resistance
Answer: C
Rationale: Every branch of a parallel circuit is connected directly across the same two
points, so each branch sees the same applied voltage.
10. What happens to total resistance when additional resistors are added in parallel?
A) It increases
B) It decreases
C) It stays the same
D) It becomes infinite
Answer: B
Rationale: Adding parallel paths gives current more routes to flow, which always
lowers total circuit resistance below the value of the smallest branch resistor.
11. Which meter is used to measure current in a live circuit without breaking the
circuit open?
A) Ohmmeter
B) Clamp-on ammeter
C) Voltmeter
D) Megohmmeter
Answer: B
Rationale: A clamp-on ammeter senses the magnetic field around a single energized
conductor, allowing current measurement without disconnecting any wiring.
12. What does the term "continuity" refer to when testing a component?
A) The presence of voltage
B) An unbroken, complete path for current flow
C) Excess resistance in a circuit
D) A grounded condition
Answer: B
