🔍 Key Concepts
• Count the number of leads/terminals on each device and relate that to how many connections a bipolar junction transistor (BJT) requires (emitter, base, collector).
• Recognize common package styles: small diode, bridge rectifier, power diode, and transistor/MOSFET packages.
• Think about which devices normally have two leads, which have three leads, and which have four or many leads.
💭 Think About
• Which pictured devices are clearly NOT BJTs based on having only two leads or many leads? Eliminate those first.
• Among the remaining pictures, which package style most commonly represents a three‑terminal transistor used for switching or amplification?
• Look for the device whose metal tab or mounting hole is often used as a heat sink for a three‑lead transistor package.
✅ Before You Answer
• Verify that a BJT must have three electrical connections: emitter, base, and collector.
• Confirm which illustration shows exactly three leads coming out of the plastic body (ignoring any mounting hole or tab).
• Double‑check that the devices you ruled out are recognized forms of diodes, bridge rectifiers, or integrated circuits, not discrete BJTs.