what is electricity - SparkFun Learning (2023)

starting

Electricity is all around us, powering technology like our cell phones, computers, lights, welders and air conditioners. It's hard to escape this in our modern world. Even when you try to escape electricity, it continues to work throughout nature, from lightning in a thunderstorm to the synapses inside our bodies. but what exactlyeselectricity? This is a very complicated question, and as you dig deeper and ask more questions, there really isn't a definitive answer, just abstract representations of how electricity interacts with our environment.

Electricity is a natural phenomenon that occurs throughout nature and takes many different forms. In this tutorial we're going to focus on current electricity: what powers our electronic devices. Our goal is to understand how electricity flows from a power source through wires, lighting LEDs, turning motors, and powering our communication devices.

Electricity is briefly defined as theelectric charge flow,but there is much behind that simple statement. Where do the charges come from? How do we move them? Where do they move? How does an electrical charge cause mechanical motion or make things light up? Many questions! To begin to explain what electricity is, we must look far beyond matter and molecules to the atoms that make up everything we interact with in life.

This tutorial is based on a basic understanding of physics,force,Energy,atoms, and [fields](http://en.wikipedia.org/wiki/Field_(physics)) in particular. We'll skip the basics of each of these physics concepts, but it might be helpful to consult other sources as well.

going atomic

To understand the basics of electricity, we must start by focusing on atoms, one of the building blocks of life and matter. Atoms exist in over a hundred different forms as chemical elements such as hydrogen, carbon, oxygen, and copper. Atoms of many types can combine to form molecules, which form the matter we can physically see and touch.

the atoms aretiny, extending to a maximum of about 300 picometers in length (that's 3x10^-10or 0.0000000003 meters). A copper penny (if it were really made of 100% copper) would be 3.2 x 10²²atoms (32,000,000,000,000,000,000,000 atoms) of copper inside.

Even the atom is not small enough to explain how electricity works. We need to dive in one more level and look at the basic building blocks of atoms: protons, neutrons and electrons.

building blocks of atoms

An atom is built from a combination of three different particles: electrons, protons and neutrons. Each atom has a central nucleus, where protons and neutrons are densely packed. Around the nucleus is a group of orbiting electrons.

A very simple atomic model. Not to scale, but useful for understanding how an atom is built. A central nucleus of protons and neutrons is surrounded by orbiting electrons.

Every atom must have at least one proton in it. The number of protons in an atom is important because it defines which chemical element the atom represents. For example, an atom with a single proton is hydrogen, an atom with 29 protons is copper, and an atom with 94 protons is plutonium. This proton count is called an atom.atomic number.

The proton's companion to the nucleus, the neutrons, serve an important purpose; they keep the protons in the nucleus and determine the isotope of an atom. They are not critical to our understanding of electricity, so we won't be concerned with them in this tutorial.

Electrons are fundamental to how electricity works (see a common theme in their names?) In its most stable, balanced state, an atom will have the same number of electrons and protons. How notbohr atomic modelbelow, a nucleus with 29 protons (making it a copper atom) is surrounded by an equal number of electrons.

As our understanding of atoms has evolved, so has our method of modeling them. The Bohr model is a very useful atomic model when exploring electricity.

The electrons in the atom are not all forever bound to the atom. The electrons in the outer orbit of the atom are called valence electrons. With enough external force, a valence electron can break free of the atom's orbit and break free.free electronsit allows us to move charge, which is what electricity is all about. Speaking of charges...

flowing loads

As we mentioned at the beginning of this tutorial, electricity is defined as the flow of electrical charge.To loadIt is a property of matter, just like mass, volume or density. It's measurable. Just as you can quantify how much mass something has, you can measure how much charge it has. The key concept with cargo is that it can come in two types:positive (+) or negative (-).

To move the load, we needload carriers, and this is where our knowledge of atomic particles, specifically electrons and protons, comes in handy. Electrons are always negatively charged, while protons are always positively charged. Neutrons (true to their name) are neutral, they have no charge. Both electrons and protons carry the sameamountfor free, just a different kind.

A model lithium atom (3 protons) with labeled charges.

The charge of electrons and protons is important because it gives us the means to exert a force on them. Electrostatic force!

electrostatic force

Electrostatic force (also calledLei de Coulomb) is a force operating between the charges. He states that charges of the same type repel each other, while charges of opposite types attract.Opposites attract and likes repel.

HimamountThe force acting on two charges depends on the distance between them. The closer two charges are, the greater the force becomes (either pushing or pushing away).

Thanks to electrostatic force, electrons will push other electrons and be attracted by protons. This force is part of the "glue" that holds atoms together, but it is also the tool we need to make electrons (and charges) flow!

Make the charges flow

Now we have all the tools to make the charges flow.electronsinto atoms can act as ourload bearer, because each electron carries a negative charge. If we can release an electron from an atom and force it to move, we can create electricity.

Consider the atomic model of a copper atom, one of the preferred elementary sources for charge flow. In its balanced state, copper has 29 protons in its nucleus and an equal number of electrons orbiting around it. Electrons orbit at different distances from the nucleus of the atom. Electrons closer to the nucleus feel a much stronger pull towards the center than those in distant orbits. The outermost electrons of an atom are calledvalence electrons, these require the least amount of force to break free from an atom.

This is a diagram of a copper atom: 29 protons in the nucleus, surrounded by circling bands of electrons. The electrons closest to the nucleus are difficult to remove, while the valence electron (outer ring) requires relatively little energy to be ejected from the atom.

Using enough electrostatic force on the valence electron, pushing it with another negative charge, or pulling it with a positive charge, we can force the electron out of orbit around the atom, creating a free electron.

Now consider a copper wire: matter filled with countless copper atoms. like oursfree electronit is floating in a space between atoms, it is pulled and pushed by the charges that surround it in that space. In this chaos, the free electron finally finds a new atom to bond with; in doing so, the negative charge of that electron drives another valence electron out of the atom. Now, a new electron wanders through free space looking to do the same. This chain effect can continue repeatedly to create a flow of electrons calledelectric current.

A very simplified model of charges flowing through atoms to generate current.

Conductivity

Some elementary types of atoms are better than others at giving up their electrons. To get the best flow of electrons possible, we want to use atoms that don't retain their valence electrons too much. The conductivity of an element measures how tightly an electron is bound to an atom.

Elements with high conductivity, which have highly mobile electrons, are calleddrivers. These are the kinds of materials we want to use to make wires and other components that help electrons flow. Metals like copper, silver, and gold are generally our top choices for good conductors.

Elements with low conductivity are calledinsulators. Insulators serve a very important purpose: they prevent the flow of electrons. Popular insulators include glass, rubber, plastic and air.

Static Electricity or Current

Before we go any further, let's discuss the two forms that electricity can take: static or current. When working with electronics, current electricity will be much more common, but it's also important to understand static electricity.

Static electricity

Static electricity exists when opposite charges accumulate on objects separated by an insulator. Static electricity (as in "resting") exists until the two sets of opposite charges can find a way between each other to balance the system.

When the charges find a way to equalize, astatic dischargeoccurs. The attraction of the charges becomes so great that they can flow through even the best insulators (air, glass, plastic, rubber, etc.). Static discharges can be harmful depending on the medium through which the charges travel and the surfaces to which they are transferred. The equalization of charges across an air gap can cause a visible collision when moving electrons collide with electrons in the air, which become excited and release energy in the form of light.

incendiariesare used to create a controlled static discharge. Opposite charges build up on each of the conductors until their attraction is so great that the charges can flow through the air.

One of the most dramatic examples of static discharge islighting. When a cloud system gathers enough charge relative to another cloud group or the Earth's ground, the charges will try to equalize. As the cloud discharges, large amounts of positive (or sometimes negative) charges travel through the air from the ground into the cloud, causing the visible effect we are all familiar with.

Static electricity also familiarly exists when we rub balloons on our heads to make our hair stand on end, or whenshuffle on the floorin fuzzy slippers and surprising the family cat (by accident, of course). In each case, the friction of friction between different types of materials transfers electrons. The object that loses electrons becomes positively charged, while the object that gains electrons becomes negatively charged. The two objects are attracted to each other until they find a way to combine.

When working with electronics, we usually don't have to deal with static electricity. When we do this, we are usually trying to protect our sensitive electronic components from being subjected to static discharge. Preventive measures against static electricity include wearing ESD (Electrostatic Discharge) wrist straps or adding special components in circuits to protect against very high surge loads.

current electricity

Current electricity is the form of electricity that makes all of our electronic devices possible. This form of electricity exists when charges are capable ofsteady flow. Unlike static electricity where charges accumulate and remain at rest, current electricity is dynamic, charges are always in motion. We'll focus on this form of electricity for the rest of the tutorial.

circuits

To flow, electric current requires athe circuit: an endless closed loop of conductive material. A circuit can be as simple as a conducting wire connected end to end, but useful circuits often contain a combination of wires and other components that control the flow of electricity. The only rule when it comes to making circuits is thatthere can be no insulation gapson them.

If you have a wire full of copper atoms and you want to induce a flow of electrons through it,allthe free electrons need somewhere to flow in the same general direction. Copper is a great conductor, perfect for making charges flow. If a copper wire circuit breaks, charges cannot flow through the air, which will also prevent charges towards the center from getting anywhere.

On the other hand, if the wire were connected end to end, all the electrons would have a neighboring atom and they could all flow in the same general direction.

now we understandWhatelectrons can flow, but how do we get them to flow in the first place? So once electrons are flowing, how do they produce the energy needed to power light bulbs or turn motors? For that, we need to understand electric fields.

electric fields

We have an idea of ​​how electrons flow through matter to create electricity. That's all there is to electricity. Well, almost everyone. Now we need a source to induce the flow of electrons. Often this source of electron flow will come from an electric field.

What is a field?

ANcampois a tool we use to model physical interactions thatinvolves no observable contact. The fields are not seen because they have no physical appearance, but the effect they have is very real.

We are all subconsciously familiar with a certain field:earth's gravitational field, the effect of a massive body attracting other bodies. The Earth's gravitational field can be modeled with a set of vectors that all point towards the center of the planet; no matter where you are on the surface, you will feel the force pulling you towards it.

The strength or intensity of the fields is not uniform at all points in the field. The farther you are from the field's source, the less effect the field has. The magnitude of Earth's gravitational field decreases as you move away from the center of the planet.

When exploring electric fields in particular, remember how the 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 for understanding how electricity starts and continues to flow. electric fieldsdescribe the pulling or pushing force on a space between charges. Compared to Earth's gravitational field, electric fields have a big difference: while Earth's field usually only attracts other mass objects (since everything isas soon assignificantly less massive), electric fields push charges away as often as they attract them.

The direction of electric fields is always defined as thedirection in which a positive test charge would moveif it was played in the field. The test charge must be infinitely small, to prevent your charge from influencing the field.

We can start by constructing electric fields for isolated positive and negative charges. If you drop a positive test charge near a negative charge, the test charge will be attracted to thenegativeto charge. So for a single negative charge, we draw our electric field arrowspointing atin all directions. That same burden of proof fell close to anotherpositivecharge would result in an outward repulsion, which means we drawarrows coming outof the positive charge.

The electric fields of individual charges. A negative charge has an internal electric field because it attracts positive charges. The positive charge has an external electric field, pushing like charges away.

Groups of electric charges can combine to form more complete electric fields.

The uniform electronic field above points away from the positive charges, towards the negative ones. Imagine a small positive test charge falling into the electronic field; You must follow the direction of the arrows. As we have seen, electricity generally involves the flow of electrons (negative charges) flowingcontraelectric fields.

Electric fields provide us with the buoyant force we need to induce current to flow. An electric field in a circuit is like an electron pump: a large source of negative charges that can trigger electrons, which will flow through the circuit into the mass of positive charges.

electric potential energy)

When we harness electricity to power our circuits, appliances, and devices, we are actually transforming energy. Electronic circuits must be able to store energy and transfer it to other forms such as heat, light or motion. The energy stored in a circuit is called electrical 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 doit workson another object, which means moving that object a certain distance. the energy entersmany ways, some we can see (like mechanical) and some we can't (like chemical or electrical). Regardless of the form it is in, the energy exists in one of the twoStates: kinetic or potential.

an object haskinetic energywhen you're on the go. The amount of kinetic energy of an object depends on its mass and speed.Potential energy, on the other hand, is astored energywhen an object is at rest. Describe how much work the object could do if it were set in motion. It is an energy that we can usually control. When an object is set in motion, its potential energy is transformed into kinetic energy.

Let's use gravity again as an example. A bowling ball standing motionless on top ofcaliph's towerhas a lot of potential (stored) energy. After falling, the ball, attracted by the gravitational field, accelerates towards the ground. As the ball accelerates, potential energy is converted into kinetic energy (the energy of motion). Eventually, all the energy in the ball is converted from potential to kinetic and then to whatever it hits. When the ball is on the ground, it has very low potential energy.

electric potential energy

Just as mass in a gravitational field has gravitational potential energy, charges in an electric field have aelectric potential energy. The electric potential energy of a charge describes the amount of stored energy it has, when set in motion by an electrostatic force, this energy can be converted into kinetic energy and work can be done by the charge.

Like a bowling ball on top of a tower, a positive charge next to another positive charge has a high potential energy; if left free to move, the charge would be repelled by like charge. A positive test charge placed near a negative charge would have a low potential energy, analogous to a bowling ball on the ground.

To instill anything with potential energy, we have to doit worksmoving it at a distance. In the case of the bowling ball, the task is to lift it 163 stories against the gravity field. Likewise, work must be done to push a positive charge against the arrows of an electric field (either towards another positive charge or away from a negative charge). The further up the field the charge is, the more work you have to do. Likewise, if you try to remove a negative chargeforaa positive charge - against an electric field - you have to do work.

For any charge located in an electric field, its electric potential energy depends on the type (positive or negative), the amount of charge, and its position in the field. Electric potential energy is measured in units of joules (j).

Electric potential

Electric potential is based on electric potential.Energyto help define how muchenergy is stored in electric fields. It is another concept that helps us to model the behavior of electric fields. The electric potential isnotthe same as electric potential energy!

At any point in an electric field, the electric potential is theamount of electric potential energy divided by the amount of chargein this point. It removes the amount of charge from the equation and gives us an idea of ​​how much potential energy specific areas of the electric field can provide. Electric potential comes in units of joules per coulomb (DIRECT CURRENT), which we define asvolt(V).

In any electric field there are two points of electric potential that are of great interest to us. There is a point of high potential, where a positive charge would have the highest possible energy, and a point of low potential, where a charge would have the lowest possible energy.

One of the most common terms we discuss when evaluating electricity isVoltage. A voltage is the potential difference between two points in an electric field. Voltage gives us an idea of ​​how strong an electric field is.

With potential and potential energy under our control, we have all the necessary ingredients to generate current electricity. Let's do it!

Electricity in Action!

After studying particle physics, field theory and potential energy, we now know enough to make electricity flow. Let's make a circuit!

First let's review the ingredients we need to make electricity:

• The definition of electricity isload flow. Normally, our charges will be carried by free-flowing electrons.
• negatively chargedelectronsthey bond loosely with atoms of conductive materials. With a little push we can release electrons from atoms and make them flow in a generally uniform direction.
• a closedthe circuitconductive material provides a path for electrons to flow continuously.
• Loads are carried by aelectric field. We need a source of electric potential (voltage), which pushes electrons from a point of low potential energy to a higher potential energy.

a short circuit

Batteries are common energy sources that convert chemical energy into electrical energy. They have two terminals, which connect to the rest of the circuit. On one terminal there is an excess of negative charges, while all the positive charges merge on the other. This is an electrical potential difference waiting to act!

If we connect our wire full of conductive copper atoms to the battery, this electric field will influence the negatively charged free electrons in the copper atoms. Simultaneously pushed by the negative terminal and attracted by the positive terminal, the copper's electrons will move from atom to atom creating the flow of charge we know as electricity.

After one second of current flow, the electrons movedmuchlittle - fractions of an inch. However, the energy produced by the current flow isgigante, especially since there is nothing in this circuit that slows down the flow or consumes power. Connecting a bare conductor directly across a power source is alittle idea. Energy moves very quickly through the system and is transformed into heat in the wire, which can quickly become a molten wire or a fire.

light a lamp

Instead of wasting all that energy, not to mention destroying the battery and wire, let's build a circuit that does something useful! Generally, an electrical circuit transfers electrical energy into some other form: light, heat, motion, etc. If we connect a light bulb to the battery with wires in the middle, we have a simple and functional circuit.

Scheme: a battery (on the left) connected to a lamp (on the right); the circuit is complete when the switch is closed (above). With the circuit closed, electrons can flow, pushed from the negative terminal of the battery through the bulb to the positive terminal.

While the electrons move at a snail's pace, the electric field affects the entire circuit almost instantly (we're talking the speed of light). The electrons in the entire circuit, whether at the lowest potential, at the highest potential, or near the light bulb, are influenced by the electric field. When the switch is closed and the electrons are subjected to the electric field, all the electrons in the circuit begin to flow seemingly at the same time. The charges closest to the bulb will take a step in the circuit and begin to transform electrical energy into light (or heat).

Resources and beyond

In this tutorial, we've only uncovered a small part of the tip of the proverbial iceberg. There are still many concepts to be discovered. From here we recommend that you go directly to ourVoltage, current, resistance and Ohm's lawtutorial. Now that you know all about electric fields (voltage) and flowing electrons (current), you are well on your way to understanding the law that governs their interaction.

For more information and visualizations that explain electricity, visitthis site.

Here are some other beginner-level concept tutorials we recommend reading:

• What is a circuit?
• Electricity
• series and parallel circuits

Or maybe you would like to learn something practical? If so, check out some of these entry-level skill tutorials:

• How to use a multimeter
• work with wire
• sew with thread