Maryland Master Electrician Exam
Questions with Answers &
Rationales| Latest update
1. A circuit has a resistance of 20 ohms and a current of 5 amps. What is the
voltage?
A. 4 V
B. 25 V
C. 100 V
D. 15 V
Answer: C
Rationale: Using Ohm's Law (V = I × R): 5 A × 20 Ω = 100 V.
2. A circuit draws 10 amps at 120 volts. What is the power consumed?
A. 12 W
B. 130 W
C. 1,200 W
D. 110 W
Answer: C
Rationale: Power (P) = I × V = 10 A × 120 V = 1,200 watts.
3. Which formula correctly calculates electrical power in watts?
A. P = I / V
B. P = I × V
C. P = I + V
D. P = V / I
Answer: B
Rationale: Power equals current multiplied by voltage (P = IV) in a purely resistive
DC circuit.
,4. In a series circuit, what happens to total resistance as more resistors are
added?
A. It decreases
B. It increases
C. It stays the same
D. It becomes zero
Answer: B
Rationale: In series circuits, resistances add directly, so total resistance increases
as more resistors are added.
5. In a parallel circuit, the total resistance is always:
A. Greater than the largest resistor
B. Less than the smallest individual resistor
C. Equal to the sum of the resistors
D. Equal to the average of the resistors
Answer: B
Rationale: Parallel paths provide additional routes for current, so total resistance
is always less than the smallest branch resistance.
6. What is the standard unit of electrical resistance?
A. Watt
B. Ohm
C. Ampere
D. Volt
Answer: B
Rationale: Resistance is measured in ohms (Ω), named after Georg Ohm.
7. In a 208Y/120V three-phase system, what is the line-to-neutral (phase)
voltage?
A. 208 V
B. 120 V
C. 277 V
D. 480 V
,Answer: B
Rationale: In a wye system, phase voltage = line voltage ÷ √3, so 208 ÷ 1.732 ≈
120 V.
8. Which law states that current is directly proportional to voltage and inversely
proportional to resistance?
A. Kirchhoff's law
B. Ohm's law
C. Faraday's law
D. Lenz's law
Answer: B
Rationale: Ohm's Law (I = V/R) defines this relationship between current, voltage,
and resistance.
9. Which statement about voltage drop in a conductor is correct?
A. It is independent of conductor length
B. It increases with conductor length and current, and decreases with larger
conductor size
C. It is always negligible and can be ignored
D. It only occurs in AC circuits
Answer: B
Rationale: Voltage drop is proportional to current and conductor length
(resistance), and inversely related to conductor cross-sectional area.
10. Power factor is best defined as:
A. The ratio of real power to apparent power
B. The ratio of voltage to current
C. Total circuit impedance
D. The ratio of reactance to resistance
Answer: A
Rationale: Power factor (PF = true power ÷ apparent power) indicates how
effectively electrical power is being converted into useful work.
11. A capacitor stores electrical energy in the form of:
, A. A magnetic field
B. An electric field
C. Chemical energy
D. Thermal energy
Answer: B
Rationale: Capacitors store energy in an electric field created between their plates
when charged.
12. An inductor opposes changes in:
A. Voltage
B. Current
C. Resistance
D. Frequency
Answer: B
Rationale: Inductors resist changes in current flow by generating a counter-EMF
(back electromotive force) proportional to the rate of current change.
Wiring Methods & Materials
13. THHN insulation is typically rated for use in:
A. Wet locations only
B. Dry and damp locations, commonly used for building wiring in conduit
C. Direct burial only, without conduit
D. Submerged underwater installations only
Answer: B
Rationale: THHN is a common thermoplastic, heat-resistant conductor insulation
used for general building wiring in raceways in dry and damp locations.
14. Nonmetallic-sheathed cable (NM/Romex) is best suited for:
A. Commercial high-rise wiring throughout
B. Residential wiring in dry, non-corrosive interior locations, subject to
applicable restrictions
C. Direct underground burial without conduit
D. Hazardous (classified) locations
Questions with Answers &
Rationales| Latest update
1. A circuit has a resistance of 20 ohms and a current of 5 amps. What is the
voltage?
A. 4 V
B. 25 V
C. 100 V
D. 15 V
Answer: C
Rationale: Using Ohm's Law (V = I × R): 5 A × 20 Ω = 100 V.
2. A circuit draws 10 amps at 120 volts. What is the power consumed?
A. 12 W
B. 130 W
C. 1,200 W
D. 110 W
Answer: C
Rationale: Power (P) = I × V = 10 A × 120 V = 1,200 watts.
3. Which formula correctly calculates electrical power in watts?
A. P = I / V
B. P = I × V
C. P = I + V
D. P = V / I
Answer: B
Rationale: Power equals current multiplied by voltage (P = IV) in a purely resistive
DC circuit.
,4. In a series circuit, what happens to total resistance as more resistors are
added?
A. It decreases
B. It increases
C. It stays the same
D. It becomes zero
Answer: B
Rationale: In series circuits, resistances add directly, so total resistance increases
as more resistors are added.
5. In a parallel circuit, the total resistance is always:
A. Greater than the largest resistor
B. Less than the smallest individual resistor
C. Equal to the sum of the resistors
D. Equal to the average of the resistors
Answer: B
Rationale: Parallel paths provide additional routes for current, so total resistance
is always less than the smallest branch resistance.
6. What is the standard unit of electrical resistance?
A. Watt
B. Ohm
C. Ampere
D. Volt
Answer: B
Rationale: Resistance is measured in ohms (Ω), named after Georg Ohm.
7. In a 208Y/120V three-phase system, what is the line-to-neutral (phase)
voltage?
A. 208 V
B. 120 V
C. 277 V
D. 480 V
,Answer: B
Rationale: In a wye system, phase voltage = line voltage ÷ √3, so 208 ÷ 1.732 ≈
120 V.
8. Which law states that current is directly proportional to voltage and inversely
proportional to resistance?
A. Kirchhoff's law
B. Ohm's law
C. Faraday's law
D. Lenz's law
Answer: B
Rationale: Ohm's Law (I = V/R) defines this relationship between current, voltage,
and resistance.
9. Which statement about voltage drop in a conductor is correct?
A. It is independent of conductor length
B. It increases with conductor length and current, and decreases with larger
conductor size
C. It is always negligible and can be ignored
D. It only occurs in AC circuits
Answer: B
Rationale: Voltage drop is proportional to current and conductor length
(resistance), and inversely related to conductor cross-sectional area.
10. Power factor is best defined as:
A. The ratio of real power to apparent power
B. The ratio of voltage to current
C. Total circuit impedance
D. The ratio of reactance to resistance
Answer: A
Rationale: Power factor (PF = true power ÷ apparent power) indicates how
effectively electrical power is being converted into useful work.
11. A capacitor stores electrical energy in the form of:
, A. A magnetic field
B. An electric field
C. Chemical energy
D. Thermal energy
Answer: B
Rationale: Capacitors store energy in an electric field created between their plates
when charged.
12. An inductor opposes changes in:
A. Voltage
B. Current
C. Resistance
D. Frequency
Answer: B
Rationale: Inductors resist changes in current flow by generating a counter-EMF
(back electromotive force) proportional to the rate of current change.
Wiring Methods & Materials
13. THHN insulation is typically rated for use in:
A. Wet locations only
B. Dry and damp locations, commonly used for building wiring in conduit
C. Direct burial only, without conduit
D. Submerged underwater installations only
Answer: B
Rationale: THHN is a common thermoplastic, heat-resistant conductor insulation
used for general building wiring in raceways in dry and damp locations.
14. Nonmetallic-sheathed cable (NM/Romex) is best suited for:
A. Commercial high-rise wiring throughout
B. Residential wiring in dry, non-corrosive interior locations, subject to
applicable restrictions
C. Direct underground burial without conduit
D. Hazardous (classified) locations
