LADWP ELECTRICAL HELPER EXAM PRACTICE QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALE 2026 Q&A | INSTANT DOWNLOAD PDF
SECTION 1: BASIC ELECTRICAL THEORY AND FUNDAMENTALS
1. What is the standard unit of electrical resistance?
A. Ampere
B. Volt
C. Ohm
D. Watt
Answer: C. Ohm
Rationale: The ohm (Ω) is the SI derived unit of electrical resistance, named after German
physicist Georg Simon Ohm. It measures the opposition to current flow in a conductor.
2. According to Ohm's Law, what is the relationship between voltage, current, and
resistance?
A. V = I × R
B. V = I / R
C. V = R / I
D. V = I + R
Answer: A. V = I × R
Rationale: Ohm's Law states that voltage (V) equals current (I) multiplied by resistance (R).
This fundamental relationship governs the behavior of electrical circuits and is essential for
troubleshooting.
3. What is the power formula in a DC circuit?
A. P = V × I
B. P = V / I
C. P = I² / R
D. P = R × I
,Answer: A. P = V × I
Rationale: Power (P) in a DC circuit equals voltage multiplied by current (P = VI). This
relationship is crucial for determining power consumption and sizing electrical
components.
4. What is the SI unit of electrical power?
A. Joule
B. Watt
C. Volt-ampere
D. Horsepower
Answer: B. Watt
Rationale: The watt (W) is the SI unit of power, defined as one joule per second. In electrical
systems, it represents the rate of energy transfer or consumption.
5. Which of the following is NOT a basic electrical quantity?
A. Voltage
B. Current
C. Resistance
D. Capacitance
Answer: D. Capacitance
Rationale: While capacitance is an electrical property, the three fundamental quantities
are voltage, current, and resistance. Capacitance is a derived property related to charge
storage.
6. What is the equivalent resistance of two 10Ω resistors connected in series?
A. 5Ω
B. 10Ω
C. 15Ω
D. 20Ω
Answer: D. 20Ω
Rationale: For resistors in series, total resistance equals the sum of individual resistances:
R_total = R₁ + R₂ = 10Ω + 10Ω = 20Ω. This principle is fundamental for circuit analysis.
7. What is the equivalent resistance of two 10Ω resistors connected in parallel?
A. 5Ω
B. 10Ω
C. 15Ω
D. 20Ω
,Answer: A. 5Ω
Rationale: For parallel resistors, total resistance is calculated as 1/R_total = 1/R₁ + 1/R₂. For
two equal resistors, R_total = R/2 = 10/2 = 5Ω.
8. What is the direction of conventional current flow?
A. Positive to negative
B. Negative to positive
C. Electron flow direction
D. Alternating direction
Answer: A. Positive to negative
Rationale: Conventional current flow assumes that current flows from positive terminal to
negative terminal, opposite to actual electron flow. This convention was established before
electrons were discovered.
9. What is the actual direction of electron flow?
A. Positive to negative
B. Negative to positive
C. Both directions
D. Depends on voltage
Answer: B. Negative to positive
Rationale: Electrons, being negatively charged particles, flow from negative terminal to
positive terminal. This is opposite to conventional current flow but is the actual physical
movement.
10. What is the unit of electrical charge?
A. Coulomb
B. Ampere
C. Volt
D. Farad
Answer: A. Coulomb
Rationale: The coulomb (C) is the SI unit of electric charge. One coulomb represents
approximately 6.242 × 10¹⁸ elementary charges (electrons or protons).
11. One ampere is equivalent to:
A. One coulomb per second
B. One volt per ohm
C. One watt per volt
D. All of the above
, Answer: D. All of the above
Rationale: One ampere equals one coulomb per second, one volt per ohm, and one watt
per volt. These equivalencies demonstrate the interconnected nature of electrical units.
12. What is the color code for a 100Ω resistor with 5% tolerance?
A. Brown-black-brown
B. Brown-black-black
C. Brown-black-red
D. Brown-black-gold
Answer: A. Brown-black-brown
Rationale: The color code for 100Ω is brown (1), black (0), brown (×10). The tolerance band
would be gold (5%) if included. The third band determines the multiplier.
13. Which material is the best conductor of electricity?
A. Copper
B. Silver
C. Aluminum
D. Gold
Answer: B. Silver
Rationale: Silver has the highest electrical conductivity of any metal at room temperature.
However, copper is more commonly used due to cost considerations and adequate
conductivity.
14. What is the primary advantage of alternating current over direct current?
A. Easier to transform voltages
B. Higher efficiency
C. Lower cost
D. Safer for personnel
Answer: A. Easier to transform voltages
Rationale: AC voltage can be easily transformed using transformers, making long-distance
power transmission more efficient. This is the primary reason AC became the standard for
power distribution.
15. What is the standard frequency of AC power in the United States?
A. 50 Hz
B. 60 Hz
C. 120 Hz
D. 400 Hz
(VERIFIED ANSWERS) PLUS RATIONALE 2026 Q&A | INSTANT DOWNLOAD PDF
SECTION 1: BASIC ELECTRICAL THEORY AND FUNDAMENTALS
1. What is the standard unit of electrical resistance?
A. Ampere
B. Volt
C. Ohm
D. Watt
Answer: C. Ohm
Rationale: The ohm (Ω) is the SI derived unit of electrical resistance, named after German
physicist Georg Simon Ohm. It measures the opposition to current flow in a conductor.
2. According to Ohm's Law, what is the relationship between voltage, current, and
resistance?
A. V = I × R
B. V = I / R
C. V = R / I
D. V = I + R
Answer: A. V = I × R
Rationale: Ohm's Law states that voltage (V) equals current (I) multiplied by resistance (R).
This fundamental relationship governs the behavior of electrical circuits and is essential for
troubleshooting.
3. What is the power formula in a DC circuit?
A. P = V × I
B. P = V / I
C. P = I² / R
D. P = R × I
,Answer: A. P = V × I
Rationale: Power (P) in a DC circuit equals voltage multiplied by current (P = VI). This
relationship is crucial for determining power consumption and sizing electrical
components.
4. What is the SI unit of electrical power?
A. Joule
B. Watt
C. Volt-ampere
D. Horsepower
Answer: B. Watt
Rationale: The watt (W) is the SI unit of power, defined as one joule per second. In electrical
systems, it represents the rate of energy transfer or consumption.
5. Which of the following is NOT a basic electrical quantity?
A. Voltage
B. Current
C. Resistance
D. Capacitance
Answer: D. Capacitance
Rationale: While capacitance is an electrical property, the three fundamental quantities
are voltage, current, and resistance. Capacitance is a derived property related to charge
storage.
6. What is the equivalent resistance of two 10Ω resistors connected in series?
A. 5Ω
B. 10Ω
C. 15Ω
D. 20Ω
Answer: D. 20Ω
Rationale: For resistors in series, total resistance equals the sum of individual resistances:
R_total = R₁ + R₂ = 10Ω + 10Ω = 20Ω. This principle is fundamental for circuit analysis.
7. What is the equivalent resistance of two 10Ω resistors connected in parallel?
A. 5Ω
B. 10Ω
C. 15Ω
D. 20Ω
,Answer: A. 5Ω
Rationale: For parallel resistors, total resistance is calculated as 1/R_total = 1/R₁ + 1/R₂. For
two equal resistors, R_total = R/2 = 10/2 = 5Ω.
8. What is the direction of conventional current flow?
A. Positive to negative
B. Negative to positive
C. Electron flow direction
D. Alternating direction
Answer: A. Positive to negative
Rationale: Conventional current flow assumes that current flows from positive terminal to
negative terminal, opposite to actual electron flow. This convention was established before
electrons were discovered.
9. What is the actual direction of electron flow?
A. Positive to negative
B. Negative to positive
C. Both directions
D. Depends on voltage
Answer: B. Negative to positive
Rationale: Electrons, being negatively charged particles, flow from negative terminal to
positive terminal. This is opposite to conventional current flow but is the actual physical
movement.
10. What is the unit of electrical charge?
A. Coulomb
B. Ampere
C. Volt
D. Farad
Answer: A. Coulomb
Rationale: The coulomb (C) is the SI unit of electric charge. One coulomb represents
approximately 6.242 × 10¹⁸ elementary charges (electrons or protons).
11. One ampere is equivalent to:
A. One coulomb per second
B. One volt per ohm
C. One watt per volt
D. All of the above
, Answer: D. All of the above
Rationale: One ampere equals one coulomb per second, one volt per ohm, and one watt
per volt. These equivalencies demonstrate the interconnected nature of electrical units.
12. What is the color code for a 100Ω resistor with 5% tolerance?
A. Brown-black-brown
B. Brown-black-black
C. Brown-black-red
D. Brown-black-gold
Answer: A. Brown-black-brown
Rationale: The color code for 100Ω is brown (1), black (0), brown (×10). The tolerance band
would be gold (5%) if included. The third band determines the multiplier.
13. Which material is the best conductor of electricity?
A. Copper
B. Silver
C. Aluminum
D. Gold
Answer: B. Silver
Rationale: Silver has the highest electrical conductivity of any metal at room temperature.
However, copper is more commonly used due to cost considerations and adequate
conductivity.
14. What is the primary advantage of alternating current over direct current?
A. Easier to transform voltages
B. Higher efficiency
C. Lower cost
D. Safer for personnel
Answer: A. Easier to transform voltages
Rationale: AC voltage can be easily transformed using transformers, making long-distance
power transmission more efficient. This is the primary reason AC became the standard for
power distribution.
15. What is the standard frequency of AC power in the United States?
A. 50 Hz
B. 60 Hz
C. 120 Hz
D. 400 Hz
