What does the most commonly used diode look like?

• A. A zigzag line
• B. A line with a triangle next to it
• C. A circle with a plus sign
• D. A rectangle with a dot

Answer: (B)

Diodes conduct current in only one direction, and their schematic symbol communicates that direction clearly. The standard diode symbol shows a triangle pointing toward a vertical line. The triangle represents the anode side, the line the cathode side. When the anode is at a higher potential than the cathode, current can flow through the diode; otherwise it blocks. This line-and-triangle symbol is the most common representation you’ll see for a regular silicon diode (like the widely used signal diodes). The other shapes correspond to different components: a zigzag line is a resistor, a circle with a plus sign denotes a voltage source, and the rectangle-with-dot isn’t a diode symbol.