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Static Electricity

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Page 1: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Static Electricity

Page 2: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

What Is Static

Electricity?• A stationary electrical charge that is built up on the surface of a material

Page 3: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Two kinds of charges• After being rubbed, a

plastic ruler can attract paper scraps.

Ruler carries electric charge.

It exerts electric force on paper.

The interaction between static electric charges is called electrostatics.

This charging method is called charging by friction.

Page 4: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Where do charges come from?

Matter is made up of atoms.

++

+

––

+

Proton (positive charge)

neutron (neutral)

electron (negative charge)

atom nucleus

Page 5: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

If electrons = protons neutral

Where do charges come from?

If electrons > protons gaining electrons, negative charge

If electrons < protons losing electrons, positive charge

Page 6: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Electro-negativity

Relativeelectro-negativityranking for somecommon materialsfrom electron donatingmaterials (+, glass) toelectron acceptingmaterials (-, teflon)

• Glass• Human Hair• Nylon• Silk• Fur• Aluminum• Paper• Cotton• Copper• Rubber• PVC• Teflon

+ + + + ++ + + ++ + ++ ++

-- -- - -- - - -- - - - -

Page 7: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Rubbing materials does NOT create electric charges. It just transfers electrons from one material to the other.

Where do charges come from?

Page 8: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

When a balloon rubs a piece of wool...

Where do charges come from?

– electrons are pulled from the wool to the balloon.

The balloon has more electrons than usual.

+++++

–––––

The balloon: – charged, The wool: +charged

wool

Page 9: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Insulators and conductors

Insulators: materials that do NOT allow electrons to flow through them easily.

Insulators can be easily charged by friction as the extra electrons gained CANNOT easily escape.

Page 10: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

4 Insulators and conductors

Conductors: materials that allow electrons to flow through them easily.

Conductors CANNOT be easily charged by friction as the extra electrons gained can easily escape.

Page 11: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Induction: The production of a charge in an uncharged body by bringing a charged object close to it

When negatively charged rod is put near a metal can...

electrons of the can are pushed away from the rod.

top of the can: positive

& attraction > repulsion

+++ +

+

metal can

- --

--

----- --

buttom of the can: negative

induced charges

attraction

repulsion

Page 12: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Attraction of uncharged objects

Similarly, when charged rod is close to paper scrap...

----- --molecules of paper align.

attraction between the rod and + charge > repulsion between the rod and - charge.paper +

–+–+–+–

+–+–+–+–

attraction

repulsion

Page 13: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 14: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Static Discharge

Human body can not feel less than 2,000 volts of static discharge

Static charge built up by scuffing shoes on a carpet can exceed 20,000 volts?

Page 15: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 16: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Gas Station Fires• Carol said a static gas pump fire is blamed for

burning her daughter so badly she needed skin grafts on her legs.

• Carol had put the gas pump nozzle on automatic and re-entered her car to write a check. When her then-12-year-old daughter, wearing a sweater and jacket that may have created static electricity, reached for the nozzle, flames suddenly ignited her clothing.

Page 17: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

1 If the balloon can attract some paper scraps, which of the following cannot be the charge of paper scraps?

A Neutral B Positive

C Negative

A balloon has a negative charge when rubbed by a woollen cloth.

Page 18: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

2 During rubbing, what have been transferred between the woollen cloth and the balloon?

A Electrons B Protons

C Neutrons

A balloon has a negative charge when rubbed by woollen cloth.

Page 19: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

When a + charged rod is put near neutral object,

______________ is induced on the side of the object

near the rod and _____________ is induced on the side

away from the rod. The rod can attract the netural object

because _________ between rod and – induced charge >

the ________ between rod and + induced charge.

How does a positively charged rod attract a neutral object?

negative charge

positive charge

attraction

repulsion

Page 20: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Grounding

An object is grounded when it is connected to the earth through a connecting wire.

What is grounding?

If a charged conductor is grounded, it will become neutral.

Page 21: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Groundingb How does grounding

occur?

++++

+

When we touch a metal ball of positive charge...

electrons flow from the earth to the metal ball to neutralize the metal ball.

Metal ball becomes neutral.

Page 22: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Similarly, if the metal ball is of negative charge...

GroundingHow does grounding occur?

––––

extra electrons flow from the metal ball to the earth and the ball becomes neutral.

Page 23: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Why do gasoline tankers usually have metal chains at the back?

When cars run, their tires and bodies are usually

charged by _______. For gasoline tankers, if the

accumulated charge is large enough, _______can be

produced and _________ will occur if gasoline vapor is

ignited. Those metal chains conduct the charge on the

bodies of tankers to the _______ and avoid the danger.

friction

sparksexplosion

ground

Page 24: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Lightning

• kills more than 60 people and

• injures more than 400 people a year in the US

• one mile every five seconds

• about 20,000 C• Voltage of up to

1.2x108 volts•

Page 25: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 26: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 27: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 28: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 29: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 30: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 31: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 32: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 33: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 34: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 35: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 36: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 37: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 38: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 39: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 40: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 41: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 42: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 43: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 44: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material
Page 45: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Limit Exposure

Page 46: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Do Now

Write a paragraph about the cartoon. Tell what he is trying to do. Will it work and why? What do you think will happen? Use the following words, static electricity, lightning, electrons, positive and negative charges.

Page 47: Static Electricity What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

The End