The library

You parents have heaps of books in this stuffed home library...

Electricity

To understand the basics of electricity, it helps to first understand about atoms.

Atoms are small particles that make up all matter. They are so small that it takes billions and billions of them just to make something useful like a pencil. Inside the atom are even smaller objects called electrons, protons, and neutrons. Electrons have a negative charge (-) and the protons have a positive charge (+). The protons and neutrons stick to together in the centre of the atom, called the nucleus. The electrons spin fast around the outside. The positive charge of the protons keeps the electrons from flying off and leaving the atom.

The electrons in the atom are where electricity gets its name. In some elements, there are electrons on the outside of the atom that, when a force is applied, can come loose and move to another atom. When a bunch of atoms are together and electrons are moving from one atom to the other in the same direction, this is called electricity.

Electricity is the "flow" of electrons.

How to make electricity

We make electricity by creating an electric circuit. Let's take the case where you are turning on a light in your house: when you flip the switch "on" you are completing the electric circuit and causing electricity and electrons to flow through the light bulb, turning the light "ON."

What's in a circuit?

  • Power source: Could be a battery or your wall outlet

  • Conductor: The wires that carry the electricity from place to place

  • Load: what the electricity is powering, like the light bulb in the example above

  • Switch: The switch that connects the circuit together to start the electricity flowing

Conductors

Conductors are materials that allow electricity to flow easily. Most types of metal are good conductors, which is why we use metal for electrical wire. Copper is a good conductor and isn’t too expensive, so it's used a lot for the wiring in homes today.

Insulators

Insulators are the opposite of conductors. An insulator is a material that doesn't carry electricity. Insulators are important because they can protect us from electricity. Materials like rubber, plastic, and paper are good insulators.

Voltage

Voltage is the name for the electric force that causes electrons to flow. It's the measure of potential difference between two points in the circuit. Voltage may come from a battery or a power plant.

Current

Current is the measure of the flow of electrons in a circuit. Current is measured in Amps or Amperes.

Power (Watts)

The power or energy used by a circuit is measured in Watts. You can calculate the number of Watts by multiplying the Voltage times the Current. When your parents get their electrical bill it’s generally in kilowatt hours. This is the measurement of power over time or how much power was used that month.

Resistance

Resistance measures how well a material or object conducts electricity. Low resistance means the object conducts electricity well, high resistance means the object does not conduct electricity well.

Battery

A battery can act as a source of electricity in circuits. It stores up electric power and then provides a voltage across a circuit causing power to flow through the circuit.

Batteries use chemicals that react to produce electricity. They have a positive terminal called the cathode and a negative terminal called the anode. When a circuit with a load is placed across the anode and cathode, the chemicals react causing electricity to flow through the circuit. The chemicals in batteries only last so long, so batteries have a limited amount of electricity and eventually will run out.

Alternate and Direct Current

There are two main types of current used in electrical systems today: alternate current (AC) and direct current (DC). Batteries, and most electronics, use direct current. This is where current always flows in one direction. Power stations that generate power for our homes generate current that constantly changes direction (60 times each second). Therefore, the power that we get from our wall outlets is AC current.

Static Electricity

Sometimes electric charges can build up on the surface of objects. This is called static electricity. When you put on your clothes and they sometimes "stick" to your body or have an attraction to you, this is static electricity. When your hair sometimes goes straight up for no reason, this can be static electricity. If you rub a balloon against your clothes, you can build up a static electricity charge on the balloon that will cause it to stick to a wall.

Light

Light is a type of radiation that is visible to the eye. Light is special because it can be described as both a wave and as a stream of particles called photons.

Reflection

One of the most important ways that light acts like wave is reflection. It is reflected light that we see with our eyes. How light reflects off objects affects the colours we see as well. When a light wave hits an object, some of the wave will bounce off the surface. How reflective the surface is will determine how much light will be reflected and how much will be absorbed or transmitted.

Refraction

When light moves from one medium (like air) to another medium (like water) it will change directions. This is a “wave-like" behaviour and is called refraction. In this way light behaves like other waves such as sound waves. The speed of the light wave also changes when it moves from medium to medium. You can see an example of refraction of light in water if you put a straw in a glass of water. You will see how the straw seems to move to the side. This is the light wave bending as it enters the water.

Energy

The simplest definition of energy is "the ability to do work". Energy is how things change and move. It'severywhere around us and takes all sorts of forms. It takes energy to cook food, to drive to school, and to jump in the air.

Different forms of energy

Chemical

Chemical energy comes from atoms and molecules and how they interact.

Electrical

Electrical energy is generated by the movement of electrons.

Gravitational

Large objects such as the Earth and the Sun create gravity and gravitational energy.

Heat

Heat energy is also called thermal energy. It comes from molecules of different temperatures interacting.

Light

Light is called radiant energy. The Earth gets a lot of its energy from the light of the Sun.

Motion

Anything that is moving has energy. This is also called kinetic energy.

Nuclear

Huge amounts of nuclear energy can be generated by splitting atoms.

Potential

Potential energy is energy that is stored. One example of this is a spring that is pressed all the way down. Another example is a book sitting high on a shelf.

Measuring energy

In physics, the standard unit of measure for energy is the joule which is abbreviated as J. There are other units of measure for energy that are used throughout the world including kilowatt-hours, calories, newton-meters, therms, and foot-pounds.

The Law of Conservation of Energy

This law states that energy is never created or destroyed, it is only changed from one state to another. One example is the chemical energy in food that we turn into kinetic energy when we move.

Renewable and Non-renewable energy

As humans we use a lot of energy to drive our cars, heat and cool our houses, watch TV, and more. This energy comes from a variety of places and in a number of forms. Conservationists classify the energy we use into two types: renewable and non-renewable. Non-renewable energy uses up resources that we cannot make again. Some examples of this are petrol to run our car and coal burned in power plants. Once they are used, they are gone forever. A renewable energy source is one that can be made again. Examples of this include hydropower (water) from turbines in a dam, wind power from windmills, and solar power from the sun.