A class of these circuit elements called transferred electron devices are used in oscillators to produce microwaves. Quantum tunneling allows a class of these devices named for Leo Esaki (“eh-SAH-key”) to exhibit (10[1])negative resistance. Four of these devices are arranged in a diamond shape in a bridge rectifier. (-5[1])These (10[1])devices have an exponential I-V (“eye-vee”) relationship (-5[1])according to the Shockley equation. Past (-5[1])the breakdown voltage, these devices (-5[1])can conduct in both directions. On circuit (10[1])diagrams, these devices are represented by a triangle touching (10[1])a line. (0[1])For 10 points, name these circuit elements that only let current flow in one direction and come in a “light-emitting” type. ■END■ (10[2])