This document discusses electric current and its effects. It explains that: 1) Electronic components like batteries help power electric circuits. Batteries are made up of multiple cells connected together. 2) Batteries are used in many devices like toys, remote controls, flashlights, and transistors. Large batteries in vehicles are also made up of multiple connected cells. 3) When electric current passes through a wire, the wire heats up. The amount of heat produced depends on the material, length, and thickness of the wire. Appliances like heaters and toasters contain coils of wire that produce heat.