electric circuit
Electricity refers to a number of phenomena associated with the presence and flow of electric charge. Electricity includes such diverse things as lightning, static electricity, the current generated by a battery as it discharges, and many other influences on our daily lives. The flow or movement of charge is an electric current Figure 17.2 . Electrons or ions may carry the charge. The elementary unit of charge is the charge of a proton, which is equal in magnitude to the charge of an electron. The SI unit of charge is the coulomb C and the charge of a proton is 1.602 1019 C. The presence of an electric charge generates an electric field. Electric current is the rate of flow of charge. The SI unit for electrical current is the SI base unit called the ampere A , which is a flow rate of 1 coulomb of charge per second 1 A = 1 C/s . An electric current flows in a path, called an electric circuit. In most chemical systems, it is necessary to maintain a closed path for current to flow. The flow of charge is generated by an electrical potential difference, or potential, between two points in the circuit. Electrical potential is the ability of the electric field to do work on the charge. The SI unit of electrical potential is the volt V . When 1 coulomb of charge moves through a potential difference of 1 volt, it gains or loses 1 joule J of energy. Table 17.1 summarizes some of this information about electricity. Common Electrical Terms Quantity.