What is Electricity? . Electricity is a fundamental part of modern life, powering everything from homes to industries. But what exactly is electricity? At its core, is the movement of electrical charge, primarily carried by electrons. This phenomenon has revolutionized the way humans live, communicate, and work, making it one of the most significant scientific discoveries of all time.
Electricity is a natural phenomenon that occurs throughout nature and takes many different forms. In this tutorial we’ll focus on current electricity: the stuff that powers our electronic gadgets. Our goal is to understand how electricity flows from a power source through wires, lighting up LEDs, spinning motors, and powering our communication devices.
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Electricity is briefly defined as the flow of electric charge, but there’s so much behind that simple statement. Where do the charges come from? How do we move them? Where do they move to? How does an electric charge cause mechanical motion or make things light up? So many questions! To begin to explain what electricity is we need to zoom way in, beyond the matter and molecules, to the atoms that make up everything we interact with in life.
This tutorial builds on some basic understanding of physics, force, energy, atoms, and [fields](http://en.wikipedia.org/wiki/Field_(physics)) in particular. We’ll gloss over the basics of each of those physics concepts, but it may help to consult other sources as well.
What is Electricity & Charge?
The atom which is the basic building block of any material contains sub atomic particles. The three basic sub atomic particles are neutron, proton and electron. The neutron and proton exists in the central nucleus of the atom while the electron revolves around it in fixed orbits. The neutron as its name suggests is neutral i.e. it does not contain any charge. While, the proton and electron contains equal amount of charge but with opposite polarities.
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The proton contains positive charge while the electron contains negative charge. Of course, these polarities are conventionally assigned to them only to differentiate between them.
In a normal state, the total charge on an atom is zero because the number of electron & protons are equal & their equal amount of charges cancels each other. The protons are tightly bounded to the nucleus so they cannot move while the electrons that exist in the outer orbit called valence electrons are somewhat loosely bounded. They can be exited with enough energy to leave the orbit & flow out of the atom.
When the valence electrons are excited they release from the orbit thus leaving positive charge on the atom behind (since the negative charged electron is removed). Some elements such as metals contain loosely connected electrons called free electrons that require very low energy to move freely and the movement of such charges is called electricity.
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Flowing Charges
As we mentioned at the beginning of this tutorial, electricity is defined as the flow of electric charge. Charge is a property of matter–just like mass, volume, or density. It is measurable. Just as you can quantify how much mass something has, you can measure how much charge it has. The key concept with charge is that it can come in two types: positive (+) or negative (-).
In order to move charge we need charge carriers, and that’s where our knowledge of atomic particles–specifically electrons and protons–comes in handy. Electrons always carry a negative charge, while protons are always positively charged. Neutrons (true to their name) are neutral, they have no charge. Both electrons and protons carry the same amount of charge, just a different type.
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Electrostatic Force
According to coulomb’s law there is an electrostatic force between two charges where the opposite charges attract & same charges repel each other. The force is inversely proportional to the distance between them.
To elaborate it more precisely, positive charge push away positive charge & negative charges push away negative charges. While positive & negative charge attracts/pull-in each other.
If we use a test positive charge & place it between two charged plates i.e. positively charged & negatively charged. There is an electric field existing between these two plates. The direction of this e-field is conventionally from positive charge towards negative charge. The test charge will experience a force of repulsion from positively charged plate & a force of attraction from negatively charged plate because of coulomb’s law. Therefore we can say that a positive charge moves from higher potential (positive charged plate) to lower potential (negative charge plate) in an electric field.
This idea is used in electricity where an electric potential is applied between two ends of a conductor & the current (which is charge) flows from the higher potential towards the lower potential.
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Types of Electricity
Static or Current Electricity
Before we get much further, let’s discuss the two forms electricity can take: static or current. In working with electronics, current electricity will be much more common, but static electricity is important to understand as well.
Static Electricity
Static electricity exists when there is a build-up of opposite charges on objects separated by an insulator. Static (as in “at rest”) electricity exists until the two groups of opposite charges can find a path between each other to balance the system out.
When the charges do find a means of equalizing, a static discharge occurs. The attraction of the charges becomes so great that they can flow through even the best of insulators (air, glass, plastic, rubber, etc.). Static discharges can be harmful depending on what medium the charges travel through and to what surfaces the charges are transferring. Charges equalizing through an air gap can result in a visible shock as the traveling electrons collide with electrons in the air, which become excited and release energy in the form of light.
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One of the most dramatic examples of static discharge is lightning. When a cloud system gathers enough charge relative to either another group of clouds or the earth’s ground, the charges will try to equalize. As the cloud discharges, massive quantities of positive (or sometimes negative) charges run through the air from ground to cloud causing the visible effect we’re all familiar with.
Static electricity also familiarly exists when we rub balloons on our head to make our hair stand up, or when we shuffle on the floor with fuzzy slippers and shock the family cat (accidentally, of course). In each case, friction from rubbing different types of materials transfers electrons. The object losing electrons becomes positively charged, while the object gaining electrons becomes negatively charged. The two objects become attracted to each other until they can find a way to equalize.
Working with electronics, we generally don’t have to deal with static electricity. When we do, we’re usually trying to protect our sensitive electronic components from being subjected to a static discharge. Preventative measures against static electricity include wearing ESD (electrostatic discharge) wrist straps, or adding special components in circuits to protect against very high spikes of charge.
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Current Electricity
Current electricity is the form of electricity which makes all of our electronic gizmos possible. This form of electricity exists when charges are able to constantly flow. As opposed to static electricity where charges gather and remain at rest, current electricity is dynamic, charges are always on the move. We’ll be focusing on this form of electricity throughout the rest of the tutorial.
Circuits
In order to flow, current electricity requires a circuit: a closed, never-ending loop of conductive material. A circuit could be as simple as a conductive wire connected end-to-end, but useful circuits usually contain a mix of wire and other components which control the flow of electricity. The only rule when it comes to making circuits is they can’t have any insulating gaps in them.
If you have a wire full of copper atoms and want to induce a flow of electrons through it, all free electrons need somewhere to flow in the same general direction. Copper is a great conductor, perfect for making charges flow. If a circuit of copper wire is broken, the charges can’t flow through the air, which will also prevent any of the charges toward the middle from going anywhere.
On the other hand, if the wire were connected end-to-end, the electrons all have a neighboring atom and can all flow in the same general direction.
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We now understand how electrons can flow, but how do we get them flowing in the first place? Then, once the electrons are flowing, how do they produce the energy required to illuminate light bulbs or spin motors? For that, we need to understand electric fields.
Electric Fields
We have a handle on how electrons flow through matter to create electricity. That’s all there is to electricity. Well, almost all. Now we need a source to induce the flow of electrons. Most often that source of electron flow will come from an electric field.
What’s a Field?
A field is a tool we use to model physical interactions which don’t involve any observable contact. Fields can’t be seen as they don’t have a physical appearance, but the effect they have is very real.
We’re all subconsciously familiar with one field in particular: Earth’s gravitational field, the effect of a massive body attracting other bodies. Earth’s gravitational field can be modeled with a set of vectors all pointing into the center of the planet; regardless of where you are on the surface, you’ll feel the force pushing you towards it.
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The strength or intensity of fields isn’t uniform at all points in the field. The further you are from the source of the field the less effect the field has. The magnitude of Earth’s gravitational field decreases as you get further away from the center of the planet.
As we go on to explore electric fields in particular remember how Earth’s gravitational field works, both fields share many similarities. Gravitational fields exert a force on objects of mass, and electric fields exert a force on objects of charge.
Electric Fields
Electric fields (e-fields) are an important tool in understanding how electricity begins and continues to flow. Electric fields describe the pulling or pushing force in a space between charges. Compared to Earth’s gravitational field, electric fields have one major difference: while Earth’s field generally only attracts other objects of mass (since everything is so significantly less massive), electric fields push charges away just as often as they attract them.
The direction of electric fields is always defined as the direction a positive test charge would move if it was dropped in the field. The test charge has to be infinitely small, to keep its charge from influencing the field.
We can begin by constructing electric fields for solitary positive and negative charges. If you dropped a positive test charge near a negative charge, the test charge would be attracted towards the negative charge. So, for a single, negative charge we draw our electric field arrows pointing inward at all directions. That same test charge dropped near another positive charge would result in an outward repulsion, which means we draw arrows going out of the positive charge.
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The uniform e-field above points away from the positive charges, towards the negatives. Imagine a tiny positive test charge dropped in the e-field; it should follow the direction of the arrows. As we’ve seen, electricity usually involves the flow of electrons–negative charges–which flow against electric fields.
Electric fields provide us with the pushing force we need to induce current flow. An electric field in a circuit is like an electron pump: a large source of negative charges that can propel electrons, which will flow through the circuit towards the positive lump of charges.
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Electric Potential (Energy)
When we harness electricity to power our circuits, gizmos, and gadgets, we’re really transforming energy. Electronic circuits must be able to store energy and transfer it to other forms like heat, light, or motion. The stored energy of a circuit is called electric potential energy.
Energy? Potential Energy?
To understand potential energy we need to understand energy in general. Energy is defined as the ability of an object to do work on another object, which means moving that object some distance. Energy comes in many forms, some we can see (like mechanical) and others we can’t (like chemical or electrical). Regardless of what form it’s in, energy exists in one of two states: kinetic or potential.
An object has kinetic energy when it’s in motion. The amount of kinetic energy an object has depends on its mass and speed. Potential energy, on the other hand, is a stored energy when an object is at rest. It describes how much work the object could do if set into motion. It’s an energy we can generally control. When an object is set into motion, its potential energy transforms into kinetic energy.
Let’s go back to using gravity as an example. A bowling ball sitting motionless at the top of Khalifa tower has a lot of potential (stored) energy. Once dropped, the ball–pulled by the gravitational field–accelerates towards the ground. As the ball accelerates, potential energy is converted into kinetic energy (the energy from motion). Eventually all of the ball’s energy is converted from potential to kinetic, and then passed on to whatever it hits. When the ball is on the ground, it has a very low potential energy.
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Electric Potential Energy
Just like mass in a gravitational field has gravitational potential energy, charges in an electric field have an electric potential energy. A charge’s electric potential energy describes how much stored energy it has, when set into motion by an electrostatic force, that energy can become kinetic, and the charge can do work.
Like a bowling ball sitting at the top of a tower, a positive charge in close proximity to another positive charge has a high potential energy; left free to move, the charge would be repelled away from the like charge. A positive test charge placed near a negative charge would have low potential energy, analogous to the bowling ball on the ground.
Electrical Circuit
An electrical circuit is a complete loop of a conductor that provides a path for the flow of charge or current. It is very essential that the circuit should contain only conductors & there should be no insulators in it otherwise the electricity would not flow.
The electrical circuit can be a simple loop of conductor or having a combination of conductor & other components to do any useful work. Therefore we can classify circuits into two categories.
Short Circuit
When a simple loop of conductor is used as an electrical circuit & is power by connecting a power source to it, it is known as short circuit. The conductor directly connects both terminals of the power source & since conductors have negligible resistance, there is a huge amount of current flow through the power source.
The heavy charge flow will heat up the conductor & the power source & it will permanently damage it. The short circuit is avoided at any cost in electricity as it will damage the power source. Which is why, we use circuit breaker in our homes to protect our wiring as well as the power source. Short circuit does not have any useful application & it is an electrical hazard.
However, we can use a short circuit in controlled manner to perform spot welding & solders etc. Also using a very low voltage signal (using multimeter), we can test the continuity of a conductor. It determines any breakage in the conductor while inside its plastic insulation.
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The Science Behind Electricity
Conductors and Insulators
- Conductors: Materials like copper and aluminum that allow electrons to flow freely.
- Insulators: Substances such as rubber and plastic that resist the flow , providing safety and control.
Static vs. Current Electricity
- Static: The buildup of charge on a surface, often resulting in a spark or shock when discharged.
- Current: The steady flow of electrons through a conductor, used in powering devices.
Key Laws
- Ohm’s Law: Voltage (V) = Current (I) × Resistance (R). It defines the relationship between voltage, current, and resistance in a circuit.
- Faraday’s Law: Explains how a changing magnetic field can induce an electric current, forming the basis for electric generators.
Sources of Electricity
Renewable Energy Sources
Renewable energy sources are sustainable and replenish naturally. Examples include:
- Solar Power: Capturing sunlight using photovoltaic cells.
- Wind Power: Harnessing wind energy through turbines.
- Hydropower: Utilizing the flow of water to generate.
Non-Renewable Energy Sources
These sources are finite and contribute to environmental pollution:
- Coal and Natural Gas: Burned to produce steam, which drives turbines.
- Nuclear Energy: Uses fission reactions to generate power.
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Basic Parameters of Electricity
The electricity has three basic parameters i.e. the Volt, Ampere & Ohm. These electrical parameters are related to each other & expressed using Ohm’s Law.
V= IR
Volts = Ampere-Ohm
Where
- V = Voltage
- I = Current
- R = Resistance
Volt (Voltage or EMF)
The voltage or EMF (Electromotive force) is the pressure behind the electrons in an electrical circuit that causes it to move through it. The volt is a unit of voltage or EMF.
A one volt is the amount of voltage responsible for pushing one ampere of current through a circuit having resistance of one Ohm.
Ampere (Current)
The current is the flow of electrons in an electrical circuit. The electrons flow under the influence of the voltage between them. Ampere is the amount of electrons flowing in a unit time.
One ampere is the amount of current flowing in a circuit having resistance of one ohm when one volt of voltage is applied to it.
Ohm (Resistance)
The resistance in an electrical circuit is the property of any material to oppose the flow of current. The Ohm is the unit of resistance & it is denoted by Ω.
An electrical circuit is said to have a resistance of one ohm when a voltage of one volt moves one ampere of current through it.
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How Electricity is Generated
Power Plants: Coal, Hydro, Solar, and Wind
is generated by converting energy from various sources into electrical energy:
- Coal Power Plants: Burn coal to produce steam.
- Hydropower Stations: Use flowing water to spin turbines.
- Solar Farms: Convert sunlight directly into it .
- Wind Farms: Use wind to turn large blades connected to generators.
Electricity Transmission and Distribution
After generation, is transmitted over high-voltage power lines and distributed to homes and businesses through substations and transformers.
Electrical Power & Measurement of Electricity
The Electrical power is the electrical energy transferred per unit time. In an electrical circuit, It is equal to the product of voltage & current.
Electrical Power = Voltage x Current
P = VI
Substituting I & V using Ohm’s law we also get;
P = I2R
P = V2/R
It is SI unit is Watt named after famous Scottish inventor James Watt who invented steam engine. The electrical power is also measured in Horse Power HP which is equal to 746 Watts.
We pay our bills based on the electrical energy we consume. The unit of energy is joule but the SI unit used for measurement of electrical energy is kWh (Kilo-Watt-Hour). One kWh is equal to 3600 kilo joules of energy. This is the standard unit used for billing of electrical energy around the world.
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Applications of Electricity in Daily Life
Home Appliances
powers refrigerators, air conditioners, washing machines, and countless other devices that make daily life comfortable and efficient.
Industrial Applications
Factories use to operate machinery, automate processes, and drive innovation in manufacturing.
Advancements in Electrical Technology
Technological breakthroughs, such as electric vehicles and renewable energy solutions, are shaping a sustainable future.
Benefits
Comfort and Convenience
has transformed how we live, offering lighting, heating, cooling, and communication at the flick of a switch.
Economic Growth
supports industries, boosts productivity, and drives innovation, playing a crucial role in global economic development.
The Environmental Impact
Carbon Emissions from Non-Renewables
The heavy reliance on fossil fuels has led to significant greenhouse gas emissions, contributing to climate change.
Green Energy and Sustainable Solutions
Investments in renewable energy are reducing dependence on non-renewables, paving the way for a cleaner environment.
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FAQs About Electricity
1. What is the basic unit of electricity?
The basic unit is the Coulomb, representing the quantity of electric charge.
2. How is electricity measured?
is measured in watts (W), which represent the rate of energy consumption or production.
3. What are the main types of electricity?
The main types are static and current electricity.
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