Master Electrician Exam (NEC)General Electrical KnowledgeEasy
A master electrician is troubleshooting a resistive heating element in a 240V AC circuit. An ammeter measures 15A flowing through the element. What is the approximate power consumed by the heating element?
- A1600 W
- B360 W
- C3600 W
- D16 W
Show answer & explanationAnswer & explanation
Correct answer: C. 3600 W
For a purely resistive AC circuit, power (P) is calculated by multiplying voltage (V) by current (I). P = V * I = 240V * 15A = 3600W.
Why the other options are wrong
- A. Incorrect calculation. This might result from a miscalculation or using incorrect values.
- B. Incorrect calculation. This is off by a factor of 10.
- D. Incorrect calculation. This might result from dividing voltage by current.
Power in Resistive AC Circuits
In a purely resistive AC circuit, power is the product of the RMS voltage and RMS current, similar to DC circuits.
- P = V * I
- Units are Watts (W)
- Applies to resistive loads where current and voltage are in phase.
Memory trick: Power's a VIP: Voltage times Intensity equals Power.