Duration: 3 hours Total points: 200
Problem 8 — Digital electronics & interfacing (15 pts) Given a microcontroller GPIO pin with output high 3.3 V (max source 20 mA) driving an LED requiring 10 mA at 2.0 V forward voltage. a) (5 pts) Calculate the resistor value and nearest standard 5% resistor to use. b) (5 pts) If the LED must be driven at 40 mA, propose a simple transistor driver (specify transistor type, resistor calculations, and protection). c) (5 pts) Explain briefly why direct MCU driving at 40 mA is discouraged. electrical engineering fundamentals by vincent del toro pdf
Problem 3 — AC steady-state & phasors (18 pts) Given: Vs = 10∠0° V, series network: R=50 Ω, L=100 mH, C=10 μF, frequency f=1 kHz. a) (6 pts) Convert L and C to reactances; compute total impedance Z and current phasor I. b) (6 pts) Compute voltage phasors across each element and verify KVL. c) (6 pts) Compute real power delivered by the source and reactive power. Duration: 3 hours Total points: 200 Problem 8
Problem 4 — Resonant circuits & bandwidth (12 pts) A series RLC has R=20 Ω, L=100 μH, C chosen so resonant frequency fr = 1 MHz. a) (4 pts) Find C. b) (4 pts) Compute Q factor and bandwidth (BW). c) (4 pts) If R is halved, state qualitatively how fr, Q, and BW change. c) (5 pts) Explain briefly why direct MCU