Electrician Electrical Theory and Math 1 — Questions and Answers
Question 1: What is the formula for calculating electrical power?
- P = V / I
- P = V × I (Correct answer)
- P = I / V
- P = V + I
Correct answer: P = V × I
Power (P) in watts equals voltage (V) multiplied by current (I), expressed as P = V × I.
Question 2: A circuit has a voltage of 120V and a resistance of 20 ohms. What is the current?
- 2 amps
- 4 amps
- 6 amps (Correct answer)
- 8 amps
Correct answer: 6 amps
Using Ohm's Law, I = V/R = 120/20 = 6 amps.
Question 3: In a series circuit, how does total resistance compare to individual resistors?
- Total resistance is less than the smallest resistor
- Total resistance equals the largest resistor
- Total resistance is the sum of all resistors (Correct answer)
- Total resistance is the average of all resistors
Correct answer: Total resistance is the sum of all resistors
In a series circuit, total resistance equals the sum of all individual resistances (RT = R1 + R2 + R3...).
Question 4: What unit is used to measure electrical resistance?
- Ampere
- Volt
- Watt
- Ohm (Correct answer)
Correct answer: Ohm
Electrical resistance is measured in ohms (Ω), named after physicist Georg Simon Ohm.
Question 5: What is the power factor of a purely resistive circuit?
- 0
- 0.5
- 0.8
- 1.0 (Correct answer)
Correct answer: 1.0
A purely resistive circuit has a power factor of 1.0 because voltage and current are perfectly in phase.
Question 6: A 240V, 5kW electric heater draws how many amps?
- 10.4 amps
- 20.8 amps (Correct answer)
- 41.6 amps
- 5 amps
Correct answer: 20.8 amps
Using I = P/V = 5000/240 ≈ 20.8 amps.
Electrician Electrical Theory and Math 1
What is the formula for calculating electrical power?