Kiểm tra & Khắc phục sự cốCâu 502 / 521
A conductor with 0.2 ohms of resistance carries 15 A. How much power is dissipated as heat in that conductor?
a.3 W
b.75 W
c.0.9 W
d.45 W
Giải thích
Power in a resistance is P = I^2 x R = (15 A)^2 x 0.2 ohms = 225 x 0.2 = 45 W. Option a is I x R (a voltage, 3 V), b divides incorrectly, and c uses I x R x 0.3. Excess I^2R heating is why loose or undersized terminations overheat.
Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- Before touching conductors you believe are de-energized, what is the safest way to verify your voltage tester is trustworthy?
- For routine voltage checks at 120 V cord-and-plug receptacle outlets on a branch circuit, what CAT rating is generally the minimum appropriate category?
- You want to measure current with a DMM's internal ammeter function. Which practice is essential to avoid a dangerous fault?
- A homeowner reports a 'weird' outlet. Which instrument most quickly indicates common miswires (open ground, open neutral, reversed polarity) at a 120 V receptacle?
- Two identical 60 W, 120 V lamps are accidentally wired in series across 120 V. Approximately what voltage will a DMM read across each lamp, and how will they glow?
- You must measure current on a circuit feeding electronic (nonlinear) loads such as LED drivers and VFDs. Which meter feature gives an accurate reading?
Cập nhật gần nhất: · quy trình kiểm tra
Đội Ngũ Biên Tập PrepPass · Đối chiếu với California CSLB C-10 Electrical Trade Examination · Quy trình kiểm tra