When testing a diode with a digital multimeter, which result indicates proper diode behavior?

When testing a diode with a digital multimeter, which result indicates proper diode behavior?

• A. The diode shows low resistance in both directions.
• B. The diode shows low resistance in one direction and high resistance in the reverse direction.
• C. The diode shows high resistance in both directions.
• D. The diode shows a short circuit in both directions.

Answer: (B)

A diode should conduct in the forward direction and block in the reverse direction. When you test it with a digital multimeter, you’re looking for that asymmetry: low resistance (or a small forward voltage reading) in the direction that forward-biases the diode, and high resistance (no conduction) in the reverse direction. This pattern shows the diode is allowing current in one direction and blocking it in the other, which is exactly how a healthy diode behaves. The other patterns—low resistance in both directions, high resistance in both directions, or a short in both directions—would indicate a fault.

A diode should conduct in the forward direction and block in the reverse direction. When you test it with a digital multimeter, you’re looking for that asymmetry: low resistance (or a small forward voltage reading) in the direction that forward-biases the diode, and high resistance (no conduction) in the reverse direction. This pattern shows the diode is allowing current in one direction and blocking it in the other, which is exactly how a healthy diode behaves. The other patterns—low resistance in both directions, high resistance in both directions, or a short in both directions—would indicate a fault.