Electrician Electrical Theory and Math 2 — Questions and Answers
Question 1: In a parallel circuit, what happens to total resistance as more resistors are added?
- It increases
- It decreases (Correct answer)
- It stays the same
- It doubles
Correct answer: It decreases
Adding more resistors in parallel provides additional paths for current, reducing overall resistance.
Question 2: What is the frequency of standard AC power in the United States?
- 50 Hz
- 60 Hz (Correct answer)
- 120 Hz
- 240 Hz
Correct answer: 60 Hz
The US electrical grid operates at 60 Hz, meaning AC voltage completes 60 cycles per second.
Question 3: What is the RMS voltage of US standard household current if the peak voltage is approximately 170V?
- 85V
- 120V (Correct answer)
- 155V
- 170V
Correct answer: 120V
RMS voltage equals peak voltage multiplied by 0.707, so 170 × 0.707 ≈ 120V.
Question 4: What is the impedance of a circuit with 8 ohms resistance and 6 ohms reactance?
- 14 ohms
- 10 ohms (Correct answer)
- 7 ohms
- 2 ohms
Correct answer: 10 ohms
Impedance Z = √(R² + X²) = √(64 + 36) = √100 = 10 ohms.
Question 5: Which of the following best describes inductance in an electrical circuit?
- Opposition to change in voltage
- Opposition to change in current (Correct answer)
- Storage of electrical charge
- Dissipation of electrical energy
Correct answer: Opposition to change in current
Inductance is the property of a conductor that opposes changes in current flow, measured in henries.
Question 6: What is the total power consumed by a 120V circuit with 10 amps at a power factor of 0.8?
- 960 watts (Correct answer)
- 1200 watts
- 1500 watts
- 800 watts
Correct answer: 960 watts
True power P = V × I × PF = 120 × 10 × 0.8 = 960 watts.
Electrician Electrical Theory and Math 2
In a parallel circuit, what happens to total resistance as more resistors are added?