circuits

What entanglement is mathematically, how Bell states are built from Hadamard and CNOT, how quantum circuits compose, and why measurement on entangled subsystems looks correlated regardless of separation.

The two transistor families that built modern electronics. BJTs as current-controlled amplifiers, MOSFETs as voltage-controlled switches with a capacitor for a gate, the three operating regions of each, and the four reasons MOSFETs ended up running every digital chip.

From a single PN junction to the four-diode bridge in every wall adapter. The IV curve, rectification, Zener voltage references, fast Schottky diodes for switching supplies, LEDs and photodiodes turning current to light and back, and the five failure modes that bite real designs.