Static Electricity

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 Charge • Atoms 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 balanced • The 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 another • By 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 electrons • Become 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 Series • The 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 voltages • They 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 Generator • What charge does the dome have? • The rubber belt transfers its charge to a regulator • What charge does the belt have?

Van de Graaff Generator • The 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

Grounding • Luckily 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.

Grounding • One of the most spectacular displays of grounding is Lightning • Lightning is a build up of charges in clouds that is grounded by lightning

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 • 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

Ground-to-Cloud Lightning

Static Shocks • Although static shocks are nothing more than annoying in our daily lives, they have other implications • Jet planes • Car refueling • Electronics manufacturers • Space Travel • Cracking Rubber

Static Electricity