Batteries power flashlights by providing a flow of electricity when the circuit is completed. Here's a breakdown:
When the switch of a flashlight is pushed into the ON position, it makes contact between two contact strips, which begin a flow of electricity, powered from the battery. The batteries are connected in such a way that electricity (flow of electrons) runs between the positive and negative electrodes of the battery. This electrical current then flows through the flashlight's bulb or LED, producing light. Once the switch is turned to the off position the contact between the contact strips is lost and the flow of electricity stops.
