How should the leads be positioned when testing diodes?

• A. Black lead on positive terminal and red lead on negative terminal
• B. Red lead on positive terminal and black lead on negative terminal
• C. Both leads on negative terminal
• D. Both leads on positive terminal

Answer: (B)

When testing diodes, the correct lead positioning is to place the red lead on the positive terminal and the black lead on the negative terminal. This configuration allows for the proper forward biasing of the diode, enabling it to conduct current if it is functional.

In diode testing, the red lead typically connects to the anode (the positive side), while the black lead connects to the cathode (the negative side). This orientation aligns with how diodes are designed to operate, allowing them to permit current flow in one direction while blocking it in the opposite direction.

Using this correct lead placement enables the meter to measure the voltage drop across the diode in the forward-biased condition, which is typically around 0.6 to 0.7 volts for silicon diodes, confirming proper functionality. If the leads were reversed or placed incorrectly, the diode would not conduct as intended, leading to misleading results in the testing process.