Final answer:
An electric current is able to travel through conductive materials because these materials have free charge carriers that can move. Copper is a good conductor, silicon is a semi-conductor, and rubber is a good insulator. These materials have their specific properties based on the density of free charge carriers and their ability to conduct electricity.
Step-by-step explanation:
An electric current is able to travel through conductive materials because these materials have free charge carriers, such as electrons, that are able to move easily. When a potential difference (voltage) is applied across a conductor, the free charge carriers are set into motion, creating an electric current.
A good conductor is copper. Copper has a high density of free electrons, allowing for efficient flow of electric current. Copper is used in electrical wiring and conductors.
A semi-conductor material is silicon. Silicon has a lower density of free charge carriers compared to conductors, but can still conduct electricity under certain conditions. It is used extensively in computer chips and electronic devices.
An example of a good insulator is rubber. Insulators have tightly bound electrons, making it difficult for electric current to pass through. Rubber is used in electrical insulation to prevent the flow of electricity.