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