Electricity Primer
The following is a basic overview of electricity. This terminology and theory can be helpful for understanding anything electric. Solar energy, electric vehicles, household electric, batteries etc.
What is Electricity?
In most basic terms, electricity is the flow of electrons along a conductor.
How can electrons be a source of energy? They travel at nearly the speed of light (186,000 miles per sec), and billions of them can move at once through a wire. The combination of speed and concentration together produce significant energy.
Primary Units of Measure – Volts & Amps:
Ampere (often shortened to Amps)
- one amp of current flow is approximately equivalent to 6.2415093×1018 electrons moving past a given point in one second.
- For electrons to move in a particular direction, it is necessary for a potential difference to exist between two points
- The same number of electrons stored on an object (static charge) and not moving is one Coulomb . Coulomb is the quantity of electrons vs the rate of electron flow (amps)
Voltage (measured in Volts)
- Voltage is electric pressure exerted on electrons in a circuit. The force is known as electromotive force (emf) which is measured in volts. Electric pressure, potential difference and emf mean the same thing
Electric Power
Power is measured in watts and is the rate at which work is done.
- Power (watts) = Voltage (in volts) x current (amps)
- 1 watt represents the amount of power consumed when the difference in potential of one volt produces a current of one amp
Electric Power related to Electric Vehicles
- Power can be electrical or mechanical
- When a mechanical force is used to lift a weight, work is done. The rate at which the weight is moved is called power. Horsepower is defined in terms of moving a certain weight over a certain distance in one minute (e.g. 33,000 lb lifted 1ft in 1 min = 1 hp)
- 746 W of electric power is equal to 1 hp
- Hp rating of electric motors is arrived at by taking the voltage and multiplying it by the current drawn under full load. Power = volts x amps
What is Work?
- The unit of work or energy is the Joule (J)
- 1 Joule is the work required to produce 1 watt for 1 second
- Watts = J/s
- Work is done whenever forces causes motion – including movement of electrons through a conductor
Energy Capacity – Total Energy
Power consumed over time is quantified by the watt-hour. Multiplying watt’s by a number of hours is watt-hours. 1000 watt-hours is equivilant to a kilowatt-hour. The kilowatt-hour is commonly used as a billing unit for energy delivered to consumers by electric utility companies. watt-hours and kilowatt-hours is used for energy consumed as well as energy available, such as energy stored in a battery.
- watt-hours=watts x hours
- watt-hours = amp-hours x volts
- watt-hours = Wh
- 1000 Wh = 1 kWh (1 kilowatt-hour)
- Kilowatt hour (kWh) = 1000 watts used for a period of 1 hour
- A household electric bill, the entire month’s time is equated to one hour’s time
Terminology:
- Current flow – a flow of electrons moving along a conductor
- Conductor – A material which electricity passes easily because it has free electrons
- Circuit – A circuit is a pathway for the movement of electrons
- Coulomb – 6.2415093×1018 electrons stored on an object (static charge) and not moving is equal to one Coulomb . A Coulomb is the quantity of electrons vs the rate of electron flow (amps).
A good source for electrical formula conversions:
http://www.rapidtables.com/