Static Electricity

Yesterday… Static electricity is when a charge remains on the surface of an object Positively Charged / Negatively Charged Law of Electric Charges Charging by Friction

Learning Goals Today we will learn... Two methods of charging objects Amount of charge Strength + Size of Electric Fields What are grounds and how do they work?

Investigating charge With the following hand-out investigate two ways to charge an object. Think about: What is happening to the electrons? What are the net charges of each material? How does this relate to the Law of Electric Charge?

Charging by induction Temporary Positive Charge Neutral Ball Return to neutral state Negatively Charged Rod Think about: Is there a way to make this charge permanent?

CHARGING BY CONTACT Neutral ball Movement of electrons Negatively charged ball Negatively charged rod An object that is charged by contact will always get the same charge as the object that charges it

AMOUNT OF CHARGE NET CHARGE: The difference between the number of protons and electrons contained 12 protons + 12 electrons If two electrons are lost … what is the net charge? ELECTRIC FORCE: Attraction that pulls objects together, repulsion that pushes objects apart

ELECTRIC FIELDS Explains how a charged object can exert force on another object without touching it The space around a charged object The larger the net charge the stronger the electric field The further from the charged object, the weaker the electric field Electric forces transmitted at the speed of light Speed of light = 299 792 458 m / s

How do you remove a static charge? Ground: has a large number of charges. Can supply or remove electrons as needed. Grounds remain neutral at all times. Grounding: when the conductor is connected to the earth, allowing free flow of electrons

Overview Today we learned… How charging by induction and charging by contact occurs What the “amount of charge” is About electric fields and electric force How to remove charges using grounds

Exit Card Using what we learned today … How could you make this ‘induced charge’ permanent instead of temporary?

Homework Textbook Questions: Page 417: 1-3, 5, 6, 8