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.
Types of Electric Current
There are three types of electric current:
- Direct Current (DC): A flow of electric charge that flows in one direction is called direct current. The magnitude and direction of DC remains constant over time.
- Alternating Current (AC): Alternating current is the flow of electric charge that changes direction periodically. The magnitude and direction of AC varies with time, usually in a sinusoidal pattern.
- Pulsed DC: Pulsed DC is a type of current that flows in pulses or brief bursts. The pulses may be unidirectional or bidirectional, but they are not continuous like DC or AC currents. This type of current is often used in specialized applications such as welding and electroplating.
In addition to AC current, there are also variations in the frequency and voltage of AC current. For example, in the United States, the standard frequency of AC power is 60 Hz, while in some other countries it is 50 Hz. The voltage of AC power can also vary depending on the application, ranging from a few volts for electronic devices to tens or hundreds of thousands of volts for power transmission over long distances.
Electron Current in Nature
Electric current is a natural phenomenon that can be found in a variety of forms in the natural world. Here are some examples of electric current in nature:
- Lightning: Lightning is a powerful discharge of electric current that occurs during a thunderstorm. It is caused by the buildup of electrical charges in the atmosphere, which are discharged as a lightning bolt.
- Electric eels: Electric eels are fish that can generate electric currents of up to 600 volts. These electric currents are used by the eels to stun their prey and for navigation in murky waters.
- Electric rays: Electric rays are a type of fish that are capable of generating an electric current. They use this electric current to stun their prey and to defend themselves from predators.
- Bioelectricity: Many living organisms, including humans, generate electric currents as part of their normal biological processes. For example, the human heart generates an electrical signal that is responsible for regulating the heartbeat.
- Geoelectricity: Geoelectricity refers to the natural electric currents that exist within the Earth’s crust. These currents are caused by the movement of charged particles in the ionosphere and the magnetosphere.
- Volcanic lightning: Volcanic lightning is a rare phenomenon that occurs during a volcanic eruption. It is caused by the buildup of electrical charges in the volcanic plume, which are discharged as a lightning bolt.