NASCLA Accredited Electrical
Contractor Exam Practice Questions
And Correct Answers (Verified
Answers) Plus Rationale 2026 Q&A|
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Electrical Theory, Calculations, and Fundamentals
1. What is the unit of electrical resistance?
A. Volt
B. Ampere
C. Ohm
D. Watt
Rationale: Electrical resistance is measured in ohms (Ω), while volts
measure potential difference, amperes measure current, and watts
measure power.
2. Which formula represents Ohm's Law?
A. P = I/R
B. V = I × R
C. R = V × I
D. I = V × R
Rationale: Ohm's Law states that voltage equals current multiplied
by resistance.
3. A 120-volt circuit has a resistance of 20 ohms. What current
flows through the circuit?
,A. 2 A
B. 4 A
C. 6 A
D. 10 A
Rationale: I = V/R = 120/20 = 6 amperes.
4. What is the electrical power of a 120-volt load drawing 10
amperes?
A. 120 W
B. 600 W
C. 1,200 W
D. 12,000 W
Rationale: Power is P = V × I, so 120 × 10 = 1,200 watts.
5. Which material is commonly used as an electrical conductor
because of its high conductivity?
A. Rubber
B. Glass
C. Copper
D. PVC
Rationale: Copper has excellent electrical conductivity and is widely
used for electrical conductors.
6. What happens to current in a circuit when resistance increases
while voltage remains constant?
A. Current increases
B. Current remains constant
,C. Current decreases
D. Voltage increases
Rationale: According to Ohm's Law, I = V/R, so current decreases as
resistance increases at constant voltage.
7. In a series circuit, the current through each component is
generally:
A. Different at every component
B. Zero
C. The same
D. Equal only at the source
Rationale: A series circuit has one current path, so the same current
flows through each component.
8. In a parallel circuit, the voltage across each branch is generally:
A. Zero
B. Different from the source voltage
C. Equal to the source voltage
D. Half the source voltage
Rationale: Parallel branches are connected across the same two
points, so each branch receives the source voltage.
9. What is the primary function of a transformer?
A. Store electrical energy permanently
B. Convert AC to DC only
C. Change AC voltage levels
D. Increase conductor resistance
, Rationale: Transformers transfer AC energy between circuits and
can step voltage up or down.
10. A transformer that increases voltage from the primary to the
secondary is called a:
A. Step-down transformer
B. Isolation transformer
C. Step-up transformer
D. Current transformer only
Rationale: A step-up transformer produces a higher secondary
voltage than its primary voltage.
11. What is the formula for electrical power in a DC circuit?
A. P = R/I
B. P = V/R
C. P = V × I
D. P = V + I
Rationale: Electrical power is the product of voltage and current.
12. What does AC stand for?
A. Applied Current
B. Alternating Capacity
C. Alternating Current
D. Automatic Circuit
Rationale: AC means alternating current, in which current
periodically changes direction.
Contractor Exam Practice Questions
And Correct Answers (Verified
Answers) Plus Rationale 2026 Q&A|
Instant Download Pdf
Electrical Theory, Calculations, and Fundamentals
1. What is the unit of electrical resistance?
A. Volt
B. Ampere
C. Ohm
D. Watt
Rationale: Electrical resistance is measured in ohms (Ω), while volts
measure potential difference, amperes measure current, and watts
measure power.
2. Which formula represents Ohm's Law?
A. P = I/R
B. V = I × R
C. R = V × I
D. I = V × R
Rationale: Ohm's Law states that voltage equals current multiplied
by resistance.
3. A 120-volt circuit has a resistance of 20 ohms. What current
flows through the circuit?
,A. 2 A
B. 4 A
C. 6 A
D. 10 A
Rationale: I = V/R = 120/20 = 6 amperes.
4. What is the electrical power of a 120-volt load drawing 10
amperes?
A. 120 W
B. 600 W
C. 1,200 W
D. 12,000 W
Rationale: Power is P = V × I, so 120 × 10 = 1,200 watts.
5. Which material is commonly used as an electrical conductor
because of its high conductivity?
A. Rubber
B. Glass
C. Copper
D. PVC
Rationale: Copper has excellent electrical conductivity and is widely
used for electrical conductors.
6. What happens to current in a circuit when resistance increases
while voltage remains constant?
A. Current increases
B. Current remains constant
,C. Current decreases
D. Voltage increases
Rationale: According to Ohm's Law, I = V/R, so current decreases as
resistance increases at constant voltage.
7. In a series circuit, the current through each component is
generally:
A. Different at every component
B. Zero
C. The same
D. Equal only at the source
Rationale: A series circuit has one current path, so the same current
flows through each component.
8. In a parallel circuit, the voltage across each branch is generally:
A. Zero
B. Different from the source voltage
C. Equal to the source voltage
D. Half the source voltage
Rationale: Parallel branches are connected across the same two
points, so each branch receives the source voltage.
9. What is the primary function of a transformer?
A. Store electrical energy permanently
B. Convert AC to DC only
C. Change AC voltage levels
D. Increase conductor resistance
, Rationale: Transformers transfer AC energy between circuits and
can step voltage up or down.
10. A transformer that increases voltage from the primary to the
secondary is called a:
A. Step-down transformer
B. Isolation transformer
C. Step-up transformer
D. Current transformer only
Rationale: A step-up transformer produces a higher secondary
voltage than its primary voltage.
11. What is the formula for electrical power in a DC circuit?
A. P = R/I
B. P = V/R
C. P = V × I
D. P = V + I
Rationale: Electrical power is the product of voltage and current.
12. What does AC stand for?
A. Applied Current
B. Alternating Capacity
C. Alternating Current
D. Automatic Circuit
Rationale: AC means alternating current, in which current
periodically changes direction.
