EETC Circuit Design & Troubleshooting 5

Question 1

What is the function of a bypass capacitor placed close to an IC's power supply pin?

Accepted Answer

To filter high-frequency noise on the supply rail and provide instantaneous current to the IC

Answer

Bypass capacitors (typically 0.1µF ceramic) suppress high-frequency noise on the supply line and act as a local charge reservoir for fast current transients.

Question 2

A technician measures the voltage across each component in a series circuit: R1=5V, R2=7V, R3=4V. What should the supply voltage measure?

Accepted Answer

16V

Answer

By Kirchhoff's Voltage Law, the supply voltage equals the sum of all individual voltage drops: 5 + 7 + 4 = 16V.

Question 3

Which oscilloscope measurement is most useful for diagnosing a phase shift between input and output signals in an amplifier?

Accepted Answer

Lissajous figure (X-Y mode)

Answer

An oscilloscope in X-Y mode displays a Lissajous figure whose shape (circle, ellipse, or line) directly indicates the phase relationship between two signals.

Question 4

What is the primary cause of skin effect in AC conductors, and how does it affect circuit design at high frequencies?

Accepted Answer

Current concentrates near the conductor's surface, increasing effective resistance

Answer

At high frequencies, eddy currents force AC current to flow near the conductor surface, reducing effective cross-sectional area and increasing resistance.

Question 5

In a transistor biasing circuit, if the base-emitter junction measures 0V instead of the typical 0.6–0.7V, what has most likely occurred?

Accepted Answer

The transistor's B-E junction is open (failed)

Answer

A functional silicon BJT base-emitter junction drops approximately 0.6–0.7V; 0V across this junction indicates the junction is open (no current path exists).

(EETC) Electrical Technician Certification Practice Test

(EETC) Electrical Technician Certification Practice Test

EETC Circuit Design & Troubleshooting 5