# Demos Intro: electricity is gonna be big. Ac/Hon Physics Notes Chapter 20 Electostatics.

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demos Intro: electricity is gonna be big

Ac/Hon Physics Notes Chapter 20 Electostatics

Lesson 1 Definitions and concepts

Objectives At the end of this lesson you will be able to: – Define electric charge and explain how forces act between charged objects

Electricity! Electricity: – Flow of electrons Electrostatics – Study of electrons (and protons) standing still

The Atom and Electric Charges Electrons – Negative charge Protons – Positive charge

Electrostatic Force Like charges repel each other Unlike charges attract each other The attraction or repulsion is called: – Electrostatic Force It is a force like all other forces we’ve studied in this class – Units = ?? – Newtons

Electrostatic Force vs. Gravity Electrostatic ForceGravitational Force Field force Force due to electric chargeForce due to mass Can repel or attractCan only attract

Other fun facts All Electrons and protons are the same regardless of what kind of atom

Questions What is electric charge? What causes electrostatic force? Why do like charges repel and vice versa? – Electrostatic Force Stop asking so many questions. We have no idea. Just accept it

How do we measure electric charge? Coulombs (C) – Charles-Augustin de Coulomb (1736-1806) Charge of an electron or proton e = 1.602 × 10 -19 C + for proton -for electron How do we get more charge (more Coulombs)? Add more electrons or protons Wait – do we ever add protons? We’ll get to this later….

What is the electrical charge of an atom? Zero It has the same # of protons and electrons Zero charge  Charge Neutral

How do we give something a charge? Add or take away electrons – Protons don’t move Adding electrons – Gives negative charge Removing electrons – Gives positive charge Atoms with a missing OR extra electron are called: – Ions

Conductors and Insulators Conductors – Electrons move easily through Insulators – Electrons stay put

Charge Conservation Electrical charge can never be created or destroyed It only moves

Lesson 2 Charging objects

Objectives At the end of this lesson you will be able to: – Solve problems involving moving of charge

Lesson 2 Charging objects

Objectives At the end of this lesson you will be able to: – Solve problems involving moving of charge

Ways things get charged Conduction – 2 things touch and electrons move Induction – 2 things come close to each other and electrons get pushed or pulled – we’ll explain this more soon…

What electrons like to do If there is no force on them, electrons spread out evenly

What’s up with “Ground” Earth is big It has a lot of electrons – really a lot If a charged object comes in contact with the earth, it automatically becomes neutral We say this object has been “grounded” Explain why…

Charging Problems Do on board – A charged object comes in contact with a charge neutral object (pos and neg) – A charged object come near a charge neutral object that’s grounded and the ground is removed.

Why will a charged object attract a charge neutral object like in the paper and ruler demo Do on board

Electorsopes A tool that tells you when it is charged. Do on board

Lesson 3 Coulomb’s Law

Objectives At the end of this lesson you will be able to: – Apply Coulomb’s Law

Coulomb’s Law

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