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Electricity Basics
Electricity
The term electricity is used generically to refer to different related physical concepts:
1. Electric charge: a fundamental property of matter measured in coulombs.
2. Electric current: the rate of flow of electric charge, measured in amperes.
3. Electric potential: the potential difference in electrical energy between two points e.g. between the positive and negative terminals of a battery. It is measured in volts.
4. Electromagnetism: the relationship between electricity and magnetism, which enables electrical energy to be generated from mechanical energy (as in a generator) and vice versa (as in a motor).
Electricity can be appreciated in different ways such as lightning, sparks and static charge.
In daily life, most people use electricity to refer to what we use to power our daily lives and fulfill our energy requirements.
It is the common name we give to the energy flow we get from the grid or a battery. The technical name is: ELECTRIC CURRENT
THINK DIFFERENT
Electrical systems have many things in common with water systems, so understanding how water acts in a water system helps in understanding how electricity acts in a electrical system.
To understand a water system, there are a few things that you should know. Things such as:
How much quantity of water there is
How much force is pushing the water through the pipe
How much water is flowing through the pipe over a certain time.
It is important to measure these things in a water system, just as it is to measure similar things in an electrical system.
Electric Current
THINK DIFFERENT
When water moves through a pipe, it is said to flow. The volume of water that flows through a pipe in one unit of timeis called the flow rate. When electricity moves through a wire, it is sometimes said to flow like water but it is usually said to have a current rather than a flow rate.
To understand the meaning of amperage, it is important to remember the concept of coulomb of charge. In terms of electrons, 1 coulomb of charge is roughly equal to 6.24 x 1018. Therefore, a current of 1 ampere is 1 coulomb of charge going past a given point per second.
It is common to see in batteries the expression ampere-hour (Ah), which is a unit of electric charge. It is equal to the charge transferred by a steady current of 1A for 1h.
Let's think in practical terms:
- The current that flows through a solar-powered light may be less than 1 A, while that needed to run a large solar-powered video may be 30 A.
0.005 A is the maximum current a human body can receive without noticing.
Voltage
VOLTAGE is a quantitative expression of the potential difference in charge between two points in an electrical field.
Its symbol is V and is measured in Volts by the International Unit System.
THINK DIFFERENT
Water pressure is a measure of the force that pushes water through a pipe.
Looking at the picture, we can see a water tank at a certain height above the ground. At the bottom of this tank there is a hose. The pressure at the end of the hose is the water pressure, which can be compared to the voltage in an electrical system.
