To forward bias a standard diode using a dc source, how should the source terminals be connected to the diode terminals?

Introduction / Context:
Correct diode polarity is a daily concern in lab work and product assembly. Reversed connections can block current or damage sensitive circuits. Remembering the forward-bias rule avoids costly mistakes and debugging time.

Given Data / Assumptions:

• A simple pn-junction diode (not Zener in breakdown).
• Standard conventional current reference (from positive to negative).
• Constant dc source with proper current limiting present.

Concept / Approach:
Forward bias occurs when the external source makes the anode more positive than the cathode, reducing the junction barrier and allowing significant current to flow. Practically, connect the positive supply to the anode and the negative (return) to the cathode.

Step-by-Step Solution:
Identify diode leads: anode (A) and cathode (K, often marked with a stripe).Connect source: + to anode, − to cathode.Verify conduction with a series resistor to limit current.Observe a forward drop around 0.6–0.8 V for silicon at nominal currents.

Verification / Alternative check:
Use a multimeter in diode mode: red probe on anode, black on cathode displays forward drop; reversing shows open circuit (OL).

Why Other Options Are Wrong:
Reversing polarity places the diode in reverse bias and blocks current.

Using identical polarities on both terminals is undefined or unsafe; polarity matters for diodes.

“Either way” contradicts basic diode physics.

Common Pitfalls:
Forgetting a current-limiting resistor in test circuits; diodes can be destroyed by excessive current even when correctly oriented.

Final Answer:
+ anode, − cathode