Basic concepts of electricity

Basic concepts of electricity

What are some important things to know about electricity?

• Conductors and insulators - 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 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. Static electricity can sometimes damage electronic components. There are anti-static bags and other ways to protect components from getting damaged.

What is Electricity?

 What is Electricity?

In order 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 center 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 do we make electrons move 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."

Here are some key elements to 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

Is electricity safe?

Electricity can be dangerous. Some important things to keep in mind:

1. Never play with electricity.
2. Always follow the instructions on electrical equipment and ask your mom or dad for help if you don't understand.
3. Never stick anything but a proper plug into a wall outlet.
4. When you unplug something from the wall, don't pull on the cord, use the plug.
5. Never put electronic items into the water, especially if they are plugged in.
6. Don't place items on top of electrical cords. The cords could get damaged and cause a fire.

These are just some safety precautions to take when using electricity. If you are unsure, be sure to check with your parents or teacher.

Energy

 

Energy

What is Energy?

The simplest definition of energy is "the ability to do work". Energy is how things change and move. It's everywhere 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

Energy can take a number of different forms. Here are some examples:

• 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.

Units of Measure for 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.

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 Nonrenewable

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 nonrenewable. Nonrenewable energy uses up resources that we cannot recreate. Some examples of this are gas 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 replenished. Examples of this include hydropower from turbines in a dam, wind power from windmills, and solar power from the sun.

The more renewable power we use the better for our planet and for future generations as they won't run out of resources someday.

Fun Facts about Energy

• In 2008 about 7% of the energy used in the United States was from renewable sources.
• A modern windmill or turbine can generate enough electricity to power around 300 homes.
• People have used waterpower to grind grain for over 2,000 years.
• Geothermal power uses energy from geysers, hot springs, and volcanoes.
• The entire world could be powered for a year from the energy from the sun that falls on the Earth's surface in one hour. We just need to figure out how to harness it!