Electrical and Computer: Electrical and Electronics
Domain overview
The Electrical and Computer: Electrical and Electronics PE exam tests applied design and analysis across linear circuits, electronic devices, digital systems, power conversion, and power-system fundamentals. Expect quantitative items that combine a model with a practical constraint: choose a device rating, compute a transfer function, interpret a phasor, or check a protection setting. Answers usually hinge on one modeling decision, so state assumptions explicitly.
Core rules and concepts
- Use nodal and mesh analysis with passive sign convention; keep resistor values in ohms and source values in volts or amps before combining.
- For sinusoidal steady state, convert to phasors, use complex impedance Z_R = R, Z_L = jωL, Z_C = 1/(jωC), then return to the time domain.
- Ideal op-amp rules apply only with negative feedback: no input current and zero differential input voltage; check saturation against supply rails.
- In power work, distinguish average, reactive, and apparent power; S = P + jQ, pf = P/|S|, and balanced three-phase S = √3 V_L I_L* with consistent line/phase quantities.
- Digital items often reduce to Boolean simplification, timing, or logic-family loading; verify fan-out and noise-margin limits.
Worked example
A 10 V source feeds a 2 kΩ series resistor to node A; a 3 kΩ resistor connects A to ground. Find the Thevenin equivalent at A-ground and the voltage across a 1.8 kΩ load.
With the load removed, the divider gives V_th = 10(3)/(2 + 3) = 6.0 V. Kill the source (short it), and R_th = 2 kΩ || 3 kΩ = 1.2 kΩ. Reconnect the load: V_L = 6.0(1.8)/(1.2 + 1.8) = 3.6 V. The reasoning matters: Thevenin values are found at the open terminals, not with the load attached.
Traps that cost marks
- Mixing peak and RMS values in power calculations.
- Forgetting that a dependent source prevents ordinary resistor combination for R_th; use a test source.
- Assuming an op-amp output can exceed its rails.
- Using line voltage where phase voltage is required in a wye connection.
- Treating a diode as ideal when the item supplies a 0.7 V drop.