Science electrostatics grade 9

*The charge of the electroscope are

"In the leaves."

The lightening process #1

A (usually) negative charge builds up at the base of the cloud.

Tribos

A Greek word meaning to rub.

Lightening safety #4

A dangerous place to take shelter during a lightening storm is under a tree, as this might be the highest point of land. Also, stay away from conductors like lawnmowers, bicycles, and golf clubs.

Charles- Augustin de Coulomb

A french physicist who discovered that the closer two charged objects are, the stronger the attraction or repulsion. When charged objects are farther apart, the attraction or repulsion decreases.

Lightening rod

A metal pole with a wire attached to it that runs down to the ground.

Photocopying step #1

A positive charge is created on the drum. The drum is a photoconductor because it's an insulator, but becomes a conductor when exposed to light.

Photocopying step #4

A sheet of paper is pressed against the drum and is heated. Heat and pressure cause the toner to fuse to the paper. (In some photocopiers, the paper is also charged to help the toner stick to it)

Insulator

A solid, liquid, or gas that resists or blocks the movement of electrons.

Triboeletric series

A table that lists the electron affinity of materials. The higher a material is listed, the higher tendency it has to lose its electrons.

Moist air...

Acts as a fair conductor, fewer charges build up. (Humid days)

Adding an antistatic dryer sheet to a clothes dryer...

Adds a thin layer of waxy chemicals to the surface of the clothes so that there is less friction between the surfaces and therefore fewer opposite charges to attract eachother.

Atom

An atom is the smallest part of an element with all the element's properties.

Positively charged

An object that has fewer electrons than protons.

Negatively charged

An object that has more electrons than protons.

In charging by contact,

An originally neutral substance gains the same charge as the charged object that touched it.

The protons and neutrons

Are in the nucleus of the atom

The electrons

Are outside the nucleus (shells)

Opposite charges...

Attract.

Neutral objects are

Attracted to charged objects

How are solid materials charged?

By the transfer of electrons.

Grounding static charges...

Can help prevent sparks near flammable fuels.

Statikos

Causing to stand.

An electrostatic precipitator...

Cleans air by using static electricity to remove particulates from gases in buildings or industrial sites.

Elektron

Comes from Greek, meaning amber, which is fossilized tree resin. Amber has been used for thousands of years to study static electricity.

Examples of conductors

Copper, aluminum, iron, mercury, and other metals

Earth is a

Donator or receiver of charge; it is not affected by the electron transfer of lightening; therefore ground is always considered neutral.

Why is it called static?

Electrons remain nearly fixed in one location on the surface of the object until they are given a path to escape.

Photocopiers use...

Electrostatic principles in their operation.

Automobiles and airplanes build up...

Friction between the vehicle's outer surface and the air.

Early electrostatic generators were called

Friction machines.

What is grounding?

Grounding is the process of connecting a charged object to earth's surface. When you connect a charged object to the ground, you are giving electrons the chance to travel to or from the ground.

Electrons

Has a negative charge

Protons

Has a positive charge

Lightening storm safety #3

If no shelter is available, avoid the highest point of land, for lightening tends to strike there most. Remain in a safe place for 30 minutes after the last Thunderclap.

Normally air is an insulator, but...

If the clouds has to build up enough charge for the air to act as a fair conductor.

How to know if the storm is right above you...

If you see lightening and hear thunder at the same time.

The electroscope was invented

In 1748 by Jean Nollet.

The difference between charging by contact and charging by induction in terms of electron transfer

In charging by contact, when the charged object touches the neutral object, the electrons from the charged object is transferred to the neutral object, turning it's charge negative. In charging by induction, the charged object doesn't come in contact with the neutral object so therefore there is no electrons that are being transferred. Instead, the electrons in the charged object repel the electrons in the neutral object, inducing a positive charge.

The wimshurst machine uses...

Induction to build up charge and create sparks.

Electroscopes are

Instruments that detect static charge.

A ground strap

Is a simple way to prevent static build-up on a car. This is effective because the ground strap is metal that conducts the flow of electrons to the ground, maintaining static charge.

The point of the lightening rod...

Is to redirect a lightening strike. A stream of charged particles is highly conductive, so if lightening strikes it'll more likely strike the lightening rod than the main structure.

Lightening storm safety #2

Lightening can strike up to 15 km from where it's raining, so if you can hear thunder, you are in string distance and should look for shelter. Safe places are large buildings because they will be properly grounded if it's striked. Other safe places include buses, cars, and other vehicles, provided that the windows are rolled up and that you do not touch the metal parts of the vehicle.

Conductors

Materials that allow electron to change positions (move freely)

Fair conductors

Materials that allow only some movement of electrons.

In dry air,

More charges build up because dry air acts as an insulator. (Winter days)

The nozzle and fuel truck...

Must be grounded before they can refuel an airplane. If not, too much static charge is built in the nozzle, and if it comes too close to the plane's body, a spark could ignite the fuel, causing the plane to explode.

An airplane has...

Needle - like projections on the wing of an airplane that disperse static charges into the air. (Kewl)

Atoms are

Neutral. The # of protons in the nucleus equals the amount of the # of electrons in the shells.

Objects become charged as a result

Of the rubbing.

You can reduce the build-up of static charges by drying....

Only the same types of materials at one time. (Static charges buildup when different types of insulators ie nylon and polyester rub together)

We also use electrostatics in processes that purify and sort materials such as...

Ore separation in mining, plastics and paper recycling, and the settlement of fine particles suspended in water.

Industrial plants that also use similar techniques to remove particulate matter:

Plants that produce cement, steel, lumber, and petrochemicals.

Photocopying step #3

Plastic particles and toner are sprayed onto the drum. As the particles come out of the sprayer, they get negatively charged, so it sticks to the positively charged areas on the drum. This creates a copy of the original paper.

Grounding wires...

Prevent damage to electrical equipment.

Three smaller particles that are within an atom:

Protons, electrons, and neutrons.

The force of friction can

Remove electrons from one object and cause them to transfer to the other object.

Like charges...

Repel.

Examples of insulators

Rubber, wood, plastic, pure water, metal oxides such as rust.

Law of repulsion

States that particles with like charges repel eachother.

Law of attraction

States that particles with opposite charges attract eachother.

Conductivity

The ability of materials to allow electrons to move freely in them.

The Van de Graaff generator:

The ball that makes your hair stick up and repel eachother.

Once an object is charged,

The charges are trapped on it until they are given a path to escape.

When a charge is transferred to the top plate/knob of an electroscope,

The charges spread out over the whole structure, including the leaves.

The lightening process #4

The cloud then discharges it's excess electrons along the temporary path to the ground, creating lightening.

Thunder?

The discharge creates a rapid expansion of the air around it, causing the sound of Thunder.

Static charge/static electricity

The electrical charge that builds up on a surface

In an insulator,

The electrons are bound tightly to the nuclei, so they resist movement.

In a conductor,

The electrons aren't as tightly bound to the nuclei, and they can move away from the nuclei.

New electrons are not being created.

The electrons in each object are just being rearranged within the object or transferred to the other object.

When a negatively charged rod is brought near an electroscope,

The electrons in the electroscope are repelled by the rod and move down away from the rod, onto the metal leaves. The metal leaves both have a negative charge so they repel eachother.

What happens to the electroscope when a negatively charged rod is taken away?

The electrons in the electroscope no longer needs to repel and they flow back up and through the electroscope, and the leaves drop down, and it is neutral again.

When a positively charged object touches a neutral object,

The electrons move from the neutral object towards the positive influence, making the neutral object positive.

When a negatively charged object touches a neutral object,

The electrons move to the neutral object making it negative.

If lightening strikes a lightening rod...

The flow of electrically charged particles is directed harmlessly down to the ground so that the building is not damaged.

Friction

The force resisting the relative motion of two surfaces in contact.

The greater the charge in an electroscope,

The greater the separation between the leaves.

The higher a material in the triboeletric series,

The greater the tendency for that material to lose electrons.

Photocopying step #2

The image on the paper to be photocopied is projected onto the drum. Where the light hits the drum, the area becomes conductive, loses its charge, and becomes neutral. The dark areas remain postively charged.

Where do the electrically charged particles go when a lightening rod is striked?

The lightening rod is striked, and the electrically charged particles is directed to the ground rod (underground) by an insulated grounding wire that runs along the side of the main structure and is connected to the lightening rod.

Coulomb (C)

The metric unit for electric charge.

Conduction

The movement or transmission of electrons through a substance.

The lightening process #2

The negative charge at the base of the cloud creates a temporary positive area on the ground through the induction process.

In induction, what charge does the neutral substance gain compared to the object brought near it?

The neutral substance gains the opposite charge of the object that was brought near it because the charge in the charged object repels the same type of charge in the neutral object.

In the contact method of charging, what charge does a neutral substance gain compared to the charging object?

The neutral substance gains the same charge as the charging influence because electrons move from one object to another.

Spray paint works best if...

The object and the paint has different charges.

Spray painting

The paint coming out of the nozzle gains a negative charge through friction. The surface of the car has been given a posting charge. Unlike charges attract, so the paint is attracted to the car. There is less waste due to bounce and over spray, and the finish is smooth and in uniform.

Photocopying step #5

The paper is still charged and may be warm when it comes out the photocopier.

How an electrostatic precipitator works:

The polluted gas goes through pipes that charge the particulate matter negatively. Then the gas moves through an area that has positively charged plates. These plates attract the negative particles and removes them from the gas. The collector plates are cleaned periodically to keep the system running efficiently.

Electrostatics

The study of static electric charges.

Electron affinity

The tendency of a substance to hold on to the electrons.

Particulate matter

The tiny pollutants that the gas discharged from factories can contain

If you were to remove the clothes from the dryer before...

They were completely dry, fewer charges would be left on them.

If you rubbed cat fur and amber together...

This will cause friction, and the electrons from the cat fur will be transferred to the amber. It's not the other way around because the cat fur is listed higher in the triboeletric series, meaning it gives up its electrons more readily. In the ending, the cat fur becomes positively charged because it lost its electrons and the amber because negatively charged because it gained electrons from the cat fur.

"Photocopy"

To copy using light.

Lightening rods are used...

To prevent damage to buildings.

The speed of light...

Travels FASTER than the speed of sound (lightening vs. Thunder)

Friction occurs when...

Two surfaces rub against eachother.

What are some ways to reduce the risk of static sparks from carpets?

Using an antistatic mat for your feet, increasing the moisture in the air by using a humidifier, spraying the carpet with antistatic spray, wearing an antistatic wrist strap, and removing the carpet from the computer room.

Fuel is...

Very. Very. Explosive. Sparks are dangerous near flammable materials (like fuel), and electronic equipment.

Lightening storm safety #1

Watch for towering storm cloud formations that signal developing storms.

Examples of fair conductors

Water with dissolved minerals, moist air, human body, carbon, and soil.

A negatively charged atom

When an atom gains electrons, it becomes negatively charged.

A positively charged atom

When an atom loses electrons, it becomes positively charged.

Charging by contact occurs

When electrons transfer from the charged object to the neutral object that it touches, making the neutral object gain the same type of charge as the charging rod.

The lightening process #3

When enough charge has built up, a path of charged particles form.

Disperse

distribute or spread over a wide area. Syn: scatter