Final answer:
When a conductor is connected to a battery, chemical reactions within the battery separate charges, creating a potential difference. Electrons are repelled from the negative terminal and move through the external circuit to the positive terminal, powering devices such as headlights.
Step-by-step explanation:
The question pertains to the chemical reactions that occur when a load or conductor is connected to the positive and negative terminals of a battery, allowing electrons to flow through the external circuit. Inside the battery, chemical reactions between the electrodes and the electrolyte create a potential difference, separating charges and making one electrode negative and the other positive. The negative terminal has an excess of negative charges (electrons), which are repelled and attracted to the positive charges at the positive terminal.
In terms of a specific example, a lead-acid battery involves chemical reactions between lead, lead dioxide, and sulfuric acid. When the circuit is complete, electrons move from the negative terminal to the positive terminal through an external device (like a headlight), while positive and negative ions move within the battery to maintain charge balance and sustain the reaction. This process is what powers devices connected to the battery.