What is electricity?

Targets

At the end of this Unit you should be able to answer the following questions 

1. What are electricity and magnetism, and how can they be used safely?

1.1 What is electricity?

1.2 What is magnetism, and how is it related to electricity?

1.3 What are the dangers of electricity, and how can it be used safely?

2. How can electricity be controlled and used?

2-1 How is the electricity we use daily measured and paid for?

2.2 Do all materials allow electricity to flow through them?

2.3 How can we understand, design, and control electrical pathways?

2.4 How can we change circuits to control the amount of electricity that flows?

3. How can we use electrical circuits to build devices?

3.1 How can electrical technology be used to build devices and solve problems?

targets

Static Electricity 

Think about a time you rubbed your feet across a carpet and touched another person. Or, think about a time when you took your hat off and your hair stood on end. Or, have you pulled clothes from the dryer apart and saw a spark? 

This spark or shock is called static electricity.
One key to electricity is something very, very small.

  1. All matter is made of atoms. All atoms are made of smaller particles. 
  2. One type of smaller particle, electrons, are a key to electricity.

A build-up of electrons creates static electricity.

Another key to electricity is to know that electrons have a negative charge.

The opposite of a negative charge is a positive charge. Protons, another type of particle in the atom, carry a positive charge.

Normally, objects carry an equal number of electrons and protons and are said to have a neutral charge.

To make things simpler, we use the symbols "–" to mean negative and "+" to mean positive. 0 means neutral.


Pixabay- This girl's hair rubbed on the trampoline and became charged as electrons moved from the trampoline to her hair.

Opposite Charges Attract
Pixabay


Perhaps you have heard the saying "Opposites attract." The same is true of charges. Electrons are attracted to anything positive. A piece of wool becomes positively charged when a balloon rubs it. The balloon becomes negatively charged.

Like Charges Repel

Pixabay


When you rub the electrons from your hair on to a balloon, your hair is positively charged and each individual hair repels the other hairs so they stand on end. Or, two rubbed balloons push each other apart (repel each other) because they are both negatively charged.

Neutral Particles Attract Charged Particles

Pixabay


Normally electrons are balanced with positive charges. But, if there are too many electrons built up, they look for a positive place to move. For example, if you rub a balloon against your shirt, the rubbed surface of the balloon gathers electrons from the cloth. The balloon can stick to anything neutral or positively charged such as a wall. This is because the imbalanced electrons are trying to move from the balloon to the wall.
Another example of static electricity is lightning. In lightning, the particles in a cloud collide. The bottom part of the cloud is like a carpet. The upper part of the cloud is like a doorknob. But there is no human to create a bridge to conduct electrons between the two cloud layers. The charge continues to build up. A pathway or stream of electrons creates a bolt of lightning through the atmosphere.

The build up of a negative charge is static electricity.  The movement of negative electrons is a current. 

When you have flowing electrons, you have electricity – it's that simple!



During a thunderstorm, the bottom of a cloud becomes negative because of a big supply of electrons. Compared to the cloud, the ground is positive. Negative is attracted to positive, so electrons move from cloud to ground when lightning strikes.

  Video

View the video below to learn more about static electricity.
Science Max Season 2 Electricity.

History Connection

The first person to experiment with electricity did so 2 600 years ago! A famous Greek named Thales discovered that when amber (hard tree sap) was rubbed, it would attract things. Thales did not know it, but by rubbing the amber, he made electrons build up on the amber to give it an electric charge.