This automation industry quiz question comes from the ISA Certified Control Systems Technician (CCST) program. Certified Control System Technicians calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables. Click this link for more information about the CCST program.
A circuit has a 100 Ω resistor, a 50 Ω resistor, and a 200 Ω resistor all in parallel with each other. What is the total resistance of the circuit?
a) 28.6 Ω
b) 35.0 Ω
c) 175 Ω
d) 0.28 M Ω
e) none of the above
Click Here to Reveal the Answer
The correct answer is A, 28.6 Ω. To find the total resistance for resistors in parallel in a circuit, use the equation:
Reference: Goettsche, L.D. (Editor), Maintenance of Instruments and Systems, 2nd Edition