Difference between revisions of "Electricity and energy"
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==Characteristics of electricity== | ==Characteristics of electricity== | ||
| − | Electricity is almost always invisible, but flowing water enables us to create good comparisons and make the concept understandable. A circuit with a battery - like in the previous graphic - operates at a certain voltage and current, similarly a basic system | + | Electricity is almost always invisible, but flowing water enables us to create good comparisons and make the concept understandable. A circuit with a battery - like in the previous graphic - operates at a certain voltage and current, similarly a basic hydraulic system operates with a certain pressure and volume. |
| − | *The voltage of a in the electrical circuit is similar to the pressure in the | + | *The voltage of a in the electrical circuit is similar to the pressure in the hydraulic system. |
| − | *The current in the electrical circuit is similar to the flow in the | + | *The current in the electrical circuit is similar to the flow in the hydraulic system. |
| − | *The wires in the electrical circuit and the load create resistance. The pipes and sprinkler in the final graphic | + | *The wires in the electrical circuit and the load create resistance. The pipes and sprinkler in the final graphic also create friction. |
| + | |||
===Voltage=== | ===Voltage=== | ||
| − | Voltage is the force that moves electrons in a circuit and is measured in '''Volts (V).''' It can be thought of as electrical pressure and in a circuit with a battery the voltage is determined by the amount of energy stored in the battery. Voltage is similar to the pressure created in the | + | Voltage is the force that moves electrons in a circuit and is measured in '''Volts (V).''' It can be thought of as electrical pressure and in a circuit with a battery the voltage is determined by the amount of energy stored in the battery. Voltage is similar to the pressure created in the hydraulic system. It depends upon the amount of water in the water that it holds. |
===Current=== | ===Current=== | ||
| − | Current is the flow of electrons in a circuit and is measured in '''Amps (A).''' Current is similar to the volume of water flowing | + | Current is the flow of electrons in a circuit and is measured in '''Amps (A).''' Current is similar to the volume of water flowing in the hydraulic system. It depends upon the amount of water permitted to flow by the valve and upon the pressure in the system. |
===Resistance=== | ===Resistance=== | ||
| − | Resistance (R) is a resistance to current that is present in all materials and all electrical systems and it is measured in '''Ohms (Ω).''' If the wires in an electrical circuit are too small for the amount of current that they need to carry, it will create friction and heat. Voltage is lost as a result. Similarly the pipes through which the water flows | + | Resistance (R) is a resistance to current that is present in all materials and all electrical systems and it is measured in '''Ohms (Ω).''' If the wires in an electrical circuit are too small for the amount of current that they need to carry, it will create friction and heat. Voltage is lost as a result. Similarly the pipes through which the water flows in the hydraulic system can create friction if there is too much pressure or volume trying to pass through them. |
<gallery widths=250px> | <gallery widths=250px> | ||
| Line 48: | Line 49: | ||
==Power== | ==Power== | ||
| + | '''Power (P)''' is a measurement of work done in a unit of time. How much electricity is being consumed, which is power, in an electric circuit depends upon both the voltage and the current of the circuit. In electrical systems power is measured in '''Watts (W)''' Similarly if water flowing from the hydraulic system is used to perform work, like spinning a wheel, the power that is used will depend upon both the volume and the pressure of the water supplied. An inefficient load in an electrical system or hydraulic system will consume more power than an efficient one. | ||
| + | |||
| + | '''Electrical Power = Voltage x Current''' | ||
| + | '''Hydraulic Power = Pressure x Volume''' | ||
| + | |||
| + | <gallery widths=250px> | ||
| + | File:Power.png|'''Voltage:''' '''Left-''' Higher pressure and volume has more power and will cause the wheel to spin faster. '''Right-''' Low pressure and volume will cause the wheel to spin slowly. | ||
| + | File:Efficiency.png|'''Current:''' '''Left-''' An inefficient load will consume a lot of power. '''Right-''' An efficient load will consume little power. | ||
| + | </gallery> | ||
== Notes == | == Notes == | ||
<references/> | <references/> | ||
Revision as of 14:03, 25 September 2020
Electricity is flowing in our bodies to power our hearts, lightning strikes the earth roughly 100 strikes per second[1], and much of human productivity and also environmental destruction result from our reliance upon it. Sometimes it seems everywhere, but the reality is that there continue to be nearly a billion people without access to electricity globally. The primary issue has always been that electricity was always produced in a few select locations and then distributed out from there in an electrical grid to homes and businesses, which can be very expensive to expand. Grid-tied PV systems can be used to help reduce the environmental impacts of electricity use and off-grid PV systems can help provide energy to areas where the grid doesn’t reach as they are able to produce, store and provide energy in the form of electricity even in the most remote locations.
A PV system needs to be designed to match the characteristics of the electrical system in an area and the energy needs of the end-user. Not just designers and installers of off-grid systems need to understand electricity and energy thoroughly, but also users to make sure that they do not damage their system by using it beyond its capabilities. The main concepts that are necessary to understand are:
- Current
- Voltage
- Resistance
These are the building blocks of even the most complex electrical systems.
Contents
What is electricity?
Electricity is a force created from the basic building block of all matter - atoms. All atoms are composed of three core components - neutrons (no charge), prontons (positive charge) and electrons (negative charge). Out of these three, the only one that is able to freely move from atom to atom is the negatively charged electron. Electrons can build up in higher concentrations in some locations and create a negative charge. Or there can be a lack of electrons, which create a positive charge. Electrons desire to flow from areas of high electron concentartion to areas of low electron concentration. Not all atoms or materials have free electrons that can move around easily - most do not like wood, plastic rocks - we call these insulators. Metals and copper are good conductors as they have abundant free electrons.
The small static electric shocks that we receive from our cloths are the result of a difference in electrons from your body to that item - this difference is voltage. As the electrons pass from your body to that item of clothing a current is created.
Making use of electricity
Static electricity and lightning are not useful to humanity as they are not in controlled systems. Electricity needs to be contained within an electrical system comprised of circuits for it to be used properly and safely. A basic electrical circuit is a closed loop built out of the following: 1. An energy source that has or can create an imbalance of electrons between to two points, which is voltage. 2. Conductive material, like wires, that allows electrons to flow from areas of high concentration to areas of low concentration. This flow is current. 3. A load or some means of constraining electron flow. Without a load or some kind of way of restraining electron flow, the electron difference created by the energy source will quickly reach zero. This is called a short-circuit.
Characteristics of electricity
Electricity is almost always invisible, but flowing water enables us to create good comparisons and make the concept understandable. A circuit with a battery - like in the previous graphic - operates at a certain voltage and current, similarly a basic hydraulic system operates with a certain pressure and volume.
- The voltage of a in the electrical circuit is similar to the pressure in the hydraulic system.
- The current in the electrical circuit is similar to the flow in the hydraulic system.
- The wires in the electrical circuit and the load create resistance. The pipes and sprinkler in the final graphic also create friction.
Voltage
Voltage is the force that moves electrons in a circuit and is measured in Volts (V). It can be thought of as electrical pressure and in a circuit with a battery the voltage is determined by the amount of energy stored in the battery. Voltage is similar to the pressure created in the hydraulic system. It depends upon the amount of water in the water that it holds.
Current
Current is the flow of electrons in a circuit and is measured in Amps (A). Current is similar to the volume of water flowing in the hydraulic system. It depends upon the amount of water permitted to flow by the valve and upon the pressure in the system.
Resistance
Resistance (R) is a resistance to current that is present in all materials and all electrical systems and it is measured in Ohms (Ω). If the wires in an electrical circuit are too small for the amount of current that they need to carry, it will create friction and heat. Voltage is lost as a result. Similarly the pipes through which the water flows in the hydraulic system can create friction if there is too much pressure or volume trying to pass through them.
Voltage: Left- A full water tank has a lot of pressure. Right- An empty water tank has no pressure.
Current: Left- A valve that is completely open allows a high volume of water to flow. Right- A valve that is nearly shut allows a low volume of water to flow.
Resistance: Left- The valve part way open with a small pipe creating friction and reducing volume. Right- The valve part way open with a large pipe allowing the volume to easily pass through.
Power
Power (P) is a measurement of work done in a unit of time. How much electricity is being consumed, which is power, in an electric circuit depends upon both the voltage and the current of the circuit. In electrical systems power is measured in Watts (W) Similarly if water flowing from the hydraulic system is used to perform work, like spinning a wheel, the power that is used will depend upon both the volume and the pressure of the water supplied. An inefficient load in an electrical system or hydraulic system will consume more power than an efficient one.
Electrical Power = Voltage x Current Hydraulic Power = Pressure x Volume
Voltage: Left- Higher pressure and volume has more power and will cause the wheel to spin faster. Right- Low pressure and volume will cause the wheel to spin slowly.
Current: Left- An inefficient load will consume a lot of power. Right- An efficient load will consume little power.
Notes
- ↑ NOAA Lightning Flash Rate. https://sos.noaa.gov/datasets/lightning-flash-rate/
