An amplifier is a device that takes a small input signal and creates a larger output signal. This makes it most similar to a step-up transformer which takes a smaller input voltage and creates a larger output voltage.

A load is a source of resistance that converts electrical energy into another form of energy. The components of a microwave, for example, are loads that work together to convert household electricity into radation that can be used to quickly cook food.

A photovoltaic cell (also known as a solar cell) converts energy from the sun into electrical energy.

Semiconductors have valence shells that are exacly half full and can conduct electricity under some conditions but not others. This property makes them useful for the control of electrical current.

In the NM cable used for wiring homes, each cable has three wires inside a sheath with each wire covered in a different color of insulation to indicate its type. The wire with the black insulation is the 'hot' wire, white is the neutral wire, and the ground wire is either covered in green insulation or left bare.