🔍 Key Concepts

• Compare the symbol shapes for thyristor/SCR, triac, and diac in basic electronics references • An SCR symbol looks like a diode (anode to cathode) with an extra gate lead coming into the junction • Note the terminal labels commonly used on an SCR: A (anode), K (cathode), and G (gate)

💭 Think About

• Which numbered symbol shows a single-direction diode path with a third control lead entering near the junction? • Which symbols instead show two opposite arrows/diodes or terminals labeled MT1/MT2 (typical of a triac), indicating bidirectional conduction? • Which symbol has its terminals explicitly labeled with some combination of A, K, and G rather than MT1/MT2 or B1/B2/E?

✅ Before You Answer

• Identify the one symbol that has only one main diode direction (not bidirectional) plus a separate gate lead • Verify the terminal labels: an SCR should use A, K, and G • Eliminate any symbol that shows two back-to-back diodes or main terminals labeled MT1 and MT2, which would not be a simple SCR