Static Electricity

Matter and Energy Review

Before we learn about static electricity, we need to do a little review of some chemistry

Matter is anything that has mass and takes up space

Energy is anything that can exert (push) a force onto another object

Matter Review

Matter is made of atoms

Atoms are made of protons, neutrons, and electrons

Electrons are VERY far away from the nucleus

Electrons

Because electrons are so far away, they have the ability to ‘jump’ around from atom to atom

When electrons jump from atom to atom it is called a separation of charges

Important to remember – electrons have a NEGATIVE charge

Electrons and ChargeAtoms usually have the same number of protons (positive) and electrons (negative)

If you think of this like a balance, it means the charges in atoms are usually balancedThe overall charge is zero

Positives and Negatives balance and make an overall charge of ZERO

Electrons and Charge

However, if electrons ‘jump’ to a different atom, it leaves a charge.

Now there are more positives than negatives

This leaves an overall POSITIVE charge

Losing electrons leaves an overall POSITIVE charge

Electrons and Charge

If electrons ‘jump’ onto an atom, it will end up with more electrons

More electrons means more negative charges

A higher number of negative charges leaves an overall NEGATIVE charge Gaining electrons leaves

an overall NEGATIVE charge

Moving Electrons

One of the easiest ways to create a separation of charges is to rub 2 objects together

When materials are in contact, the electrons can ‘jump’ from one material to anotherBy adding a little energy, it helps the electrons jump

Static Electricity

When there is a separation of charges, it is called Static Electricity

Static Electricity is charges built up on the surface of an object

These charges stay there until they are discharged

Moving Electrons

If you rub 2 materials together, one object will lose electrons It will get a positive charge

The other object will gain electrons It will get a negative charge

Holding Electrons

When you rub 2 materials together, some will hold their electrons better and are more likely to gain electronsBecome negatively charged

Some materials lose their electrons easier and are more likely to become positively charged

Electrostatic Series

We list objects on an Electrostatic Series to show how well objects will hold electrons

The higher it is on the list, the greater the tendency to lose electrons

The lower on the list, the greater the tendency to take electrons

Electrostatic Series

If you are going to rub 2 objects together, you can use an electrostatic series to see which has a positive charge and which has a negative charge

The higher object on the series becomes positive

The lower object on the series becomes negative

Electrostatic SeriesThe further away objects are on the

series, the greater the separation of charges

The greater the separation of charges, the more static electricity is created

Examples Cotton and Vinyl are rubbed together,

which becomes positive? Negative?

Which creates more static electricity, wool and acetate or nylon and polyester?

Van de Graaff Generator

A Van de Graaff Generator is a static electricity generator

It works by rubbing 2 objects together

These objects create static electricity and generate huge voltagesThey are very safe however

Van de Graaff Generator

It uses a motor to run a rubber belt

The rubber belt moves and rubs against a steel brush.

The brush transfers the charge to the metal dome

Van de Graaff GeneratorWhat charge does the dome have?

The rubber belt transfers its charge to a regulator What charge does the belt have?

Van de Graaff GeneratorThe dome takes on an overall positive charge

The regulator builds up an overall negative charge

This charge can be transferred if you touch the dome

Volunteers? If you want to try out the Van de Graaff, we will try making a

chain of people to see how the charge is transferred

If you have heart problems or a pacemaker, please do not participate

Remove your cell phones, iPods, and electronics just in case the static electricity discharges into your devices and wrecks it

You do not HAVE to participate but I guarantee that you will live through this

Why did we get shocked?

Like I had mentioned, electricity builds up on a surface until it can discharge

Electricity basically discharges to reset the build up of positives and negatives

This is done by making electrons flow toward the positive charge

For electrons to flow, we need a place to store lots of positive or negative charges

GroundingLuckily the Earth has a huge

storage of lots of positive and negative charges

If we make a connection to the Earth, it causes electrons to flow to the positive charge

This is called grounding.

Grounding

Grounding is the when charges flow into the ground

We often feel this as a shock when we are grounded

Grounding creates a path for electrons to flow through.

GroundingOne of the most spectacular displays of grounding is

Lightning

Lightning is a build up of charges in clouds that is grounded by lightning

Clouds are made of water vapor

If the water vapour swirls around and rubs against more water vapour or gases, it can cause a build up of negative charges in a cloud

If the charge is built up enough, it can force an area on the ground to become positively charged

• Once there is enough charge built up, the build up of electrons shoots down from the cloud into the positive in the ground.

• This grounds the cloud and forms lightning

Ground-to-Cloud Lightning

Static Shocks

Although static shocks are nothing more than annoying in our daily lives, they have other implicationsJet planesCar refuelingElectronics manufacturersSpace TravelCracking Rubber