Back To CourseThermodynamics Study Guide
6 chapters | 51 lessons
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Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology.
Benjamin Franklin is famous for quite a few things, but mostly for the story of his adventure with a kite in a lightning storm. This story is so famous because the events of this 'experiment' are rumored to have led to his discovery of electricity.
I'll let you ponder the validity of the story's details on your own time, but one thing is true. Franklin is considered the person who discovered electrical energy. The name is a bit of a misnomer, though, because electrical energy itself (often called electricity) isn't really a form of energy. It's more a way that energy is transferred between objects. In its most bare-bones form, electricity is the transfer of energy between electrons.
Everything on Earth has electrons because everything is made of atoms. Atoms come with three main components: protons and neutrons in the nucleus and electrons orbiting around that nucleus. Like their names imply, neutrons have no charge (they are neutral), protons have a positive charge, and electrons have a negative charge.
Normally an atom is balanced - the positive charge from its protons equals the negative charge from its electrons. Not only are these charges balanced, but much like the opposite poles of two magnets, they are attracted to each other. In contrast, two charges of the same sign (either two positive charges or two negative charges) will repel each other.
Because electrons are orbiting far from the atom's nucleus, they can easily be transferred from one object to another. For example, take a balloon and rub it on your hair. When you do this, you're transferring electrons from your hair to the balloon, which gives the balloon a net negative charge and your hair a net positive charge. This is why as you pull the balloon away, your hair stands on end trying to go with it - the charges are attracted to each other! However, do this with a second balloon and try to put them together. The balloons will repel each other because they both have an excess of electrons, which means they have a net negative charge.
Don't worry; no electrons were harmed in the making of this lesson. The same number of electrons exists throughout the balloon and hair activity, you've just transferred them from one place to another - electrical energy in action! Does this conservation concept sound familiar? It should because electricity follows the law of conservation of energy. Just like energy is never created or destroyed, electric charge is also never created or destroyed; it's only transferred from one object to another.
The movement, or 'flow,' of electric charge is called current, and the path along which electrons can flow is called a circuit. Electrons move along a circuit much like water moves through a pipe - going from one end to the other. Electrons can do this because, unlike protons, they are not stuck inside the atom's nucleus.
You can't create or destroy energy, but you can create electric current. Current comes from an electric pressure differential, something we call voltage. Let's say you have a glass full of water and you poke a hole near the bottom. Water will flow out through the hole because the pressure at the bottom of the glass is greater than the pressure at the top. Water will continue to flow out of the hole until the pressure difference is equalized in the glass.
The same is true for electrical pressure. In something like a battery, there is an electrical pressure difference between the positive and negative terminals. This creates a flow of electrons, or current, when the battery is connected to an electrical wire. The battery 'pumps' current through the circuit wire much like your heart pumps blood through your veins and arteries - the greater the voltage, the more current is produced. And much like you need your heart to exist, a voltage source is necessary for current to exist.
The whole point of sending electrons along the circuit wire is to utilize the electricity, right? Otherwise, we'd still be happily reading by candlelight and traveling in horse-drawn carriages.
Devices are placed along the circuit so that they can be powered. In your house, these are the outlets that you plug your devices into. But much like a clogged drain creates resistance against the flow of water through a pipe, these electricity 'collectors' along the circuit create resistance against electron flow through the wire. As the name implies, this is an opposition of electron movement. Both the length and width of an electrical wire affect the resistance of current running through it. The type of material is also an important factor because some materials are less restrictive to electron flow than others.
Circuits are not limited to electrical wires. As long as there is an electric pressure differential, many different things can provide a pathway for electron flow - even your own body! This is why you wouldn't want to touch a live electric fence with your hand while standing on the ground. There is a difference in voltage between the wire and the ground you stand on, and when you touch both at the same time, you complete the circuit and create a path for current flow. OUCH!
While you're standing next to that fence contemplating the pain you've just avoided, look up and observe those birds happily sitting on the electrical wire. They're perfectly fine up there! The key is that both their feet are on the same wire - there's no difference in voltage between them. In fact, if you were falling from the sky, and the only thing that could stop you was catching a live electrical wire, you'd be glad to know that this is perfectly safe!
Much like the bird does not receive a shock, neither would you as long as you don't touch the ground or any other live electrical wires. In order to receive a shock, there must be a voltage difference between two parts of your body. Just make sure you let go of the wire before setting your feet on the ground!
Benjamin Franklin may or may not have gone kite flying in a thunderstorm, but he is considered the discoverer of electrical energy. This natural process that occurs on the subatomic level is a way that energy is transferred between objects.
Electric charge moves through pathways called circuits, and the movement of the charge itself is called current. Much like blood is pumped through your arteries by your heart, current is pumped through a circuit by an electric pressure differential called voltage. Contrary to this, as the name implies, resistance is an opposition of electron movement.
Many different materials have the potential to become pathways for electron flow, even the human body. The key is a difference in voltage between two points. Without it, you're pretty safe. But once you make that connection, like grabbing onto an electric wire while standing on the ground, be prepared for a very 'shocking' experience!
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Back To CourseThermodynamics Study Guide
6 chapters | 51 lessons