Electric current is the flow of electric charge through a material. It is the rate at which electric charge flows past a point in a circuit. The flow of electric charge is typically carried by electrons, which are negatively charged particles.
The SI unit for current is the coulomb per second, or the ampere (A), which is an SI base unit:
1 ampere = 1A = 1 coulomb per second = 1 C/s.
In different current-carrying materials, the charges of the moving particles may be positive or negative. In metals, the moving charges are always (negative) electrons, while in an ionized gas (plasma) or an ionic solution, the moving charges may include both electrons and positively charged ions. In a semiconductor material such as germanium or silicon, conduction is partly by electrons and partly by motion of vacancies, also known as holes; these are sites of missing electrons and act like positive charges.
Ion current refers to a flow of electrical charge that is observed in electrolytes, wires, plasma and other conducting materials or fluids. It is a primary component in the initiation of corrosion reactions in metals. The unit of measure of ionic current is the ampere.
Ion current can be found in a wide range of natural and man-made systems, such as batteries, fuel cells, and biological systems. Here are some examples of ionic electric current:
- Electrolysis: Electrolysis is a process that involves the use of electric current to drive a non-spontaneous chemical reaction. In electrolysis, an ionic current is passed through a solution or molten material, causing ions to move to the electrodes and undergo a chemical reaction.
- Batteries: Batteries are devices that convert chemical energy into electrical energy by creating an ionic current. The chemical reaction inside the battery generates a flow of charged ions, which are transferred between the battery’s electrodes to produce a current.
- Fuel cells: Fuel cells are devices that convert chemical energy into electrical energy by creating an ionic current. In a fuel cell, a chemical reaction occurs between a fuel and an oxidizing agent, generating a flow of charged ions that are transferred between the cell’s electrodes to produce a current.
- Biological systems: Ionic current is an important component of many biological systems, such as the movement of ions across cell membranes and the transmission of nerve impulses.
Understanding the principles of ionic current is important in a wide range of fields, such as electrochemistry, materials science, and biology.