The SI unit of electric current is the ampere (A), which is equal to a flow of one coulomb of charge per second. (example- 1 C/s = 1 A) The ampere is named for the french scientist Andre Marie Ampere (1775- 1836) a device that measures current is an ammeter. The flow of positive charge is called
Electric current is the flow of electric charge. Natural examples include lightning and the solar wind, the source of the polar aurora. The most familiar artificial form of electric current is the flow of conduction electrons in metal wires, such as the overhead power lines that deliver electrical energy across long distances and the smaller wires within electrical and electronic equipment. In electronics, other forms of electric current include the flow of electrons through resistors or through the vacuum in a vacuum tube, the flow of ions inside a battery, and the flow of holes within a semiconductor. Electric current is sometimes informally referred to as amperage or ampage, by analogy with the term voltage. Though this is a valid term, some engineers frown on it.Eletric energy could come from othe sources too, a voltaic or galvanic cell converts chemical energy into electric energy. When more then one cell is joined together they form a battery. In adition a photovoltaic cell, othewise known as a solar cell, changes light into energy.
The following are some symbles used in creating a circuit schematic. A schematic is like an artist's drawing of an electric curcuit.
Ohm's law: Ohm's law predicts the current in an (ideal) resistor (or other ohmic device) to be the quotient of applied voltage over electrical resistance:
Conventional current, was defined early in the history of electrical science as a flow of positive charge. In solid metals, like wires, the positive charges are immobile, and only the negatively charged electrons flow in the direction opposite conventional current, but this is not the case in most non-metallic conductors. In other materials, charged particles flow in both directions at the same time. Electric currents in electrolytes are flows of electrically charged atoms (ions), which exist in both positive and negative varieties.
I is the current
N is number of charged particles per unit volume
A is the cross-sectional area of the conductor
V is the drift velocity
Q is the charge on each particle
t is time
R is resistance
E is thermal energy