Question 50G3

A logic probe is a fundamental tool for troubleshooting digital circuits, indicating the logic state (HIGH, LOW, or pulsing) at a test point. * **A) A “Red” LED indicates a “High” state.** This is generally true. Logic probes are typically designed with a red LED to signify a logic HIGH (near the positive supply voltage). * **C) A “Green” LED indicates a “Low” state.** This is also generally true. The green LED commonly indicates a logic LOW (near ground potential). * **D) An “Amber” LED indicates a “pulse”.** This is correct. Many logic probes feature a third LED (often amber or yellow) that flashes to indicate the presence of a pulse train or a rapidly changing logic state that might not be clearly visible on the steady red/green LEDs. * **B) Both “Red” and “Green” LEDs on indicate a short.** This statement is **false**. If a point in a circuit were shorted to ground, the green (LOW) LED would light. If it were shorted to the power supply, the red (HIGH) LED would light. Both the red and green LEDs illuminating simultaneously on a logic probe typically indicate an *undefined* or *high-impedance* (floating) state, where the voltage is not distinctly HIGH or LOW, rather than a short.