October 17 Bellwork hint coming…

• Set Up a Page for Note Taking. Templates

on front counter if you want one

• Homework:

• Read Chapter 19!

• Make sure Notes I (Vocabulary) is

completely finished

October 17 Bell Work Florence Bascom

• first woman to receive a Ph.D from John

Hopkins University

• first woman hired by the United States

Geological Survey

• Her innovation and discovery is still

influential to our modern study of geology

• Also taught as a professor of geology and

editor of the American Geologist

(magazine)

Notes II

Chapter 19 Section 1

Materials can become electrically charged

http://titaniumphysicists.brachiolopemedia.com/wp-content/uploads/2017/08/c-atom_e-1-300x250.gif

Electron: a negatively charged particle

located outside an atom’s nucleus

http://titaniumphysicists.brachiolopemedia.com/wp-content/uploads/2017/08/c-atom_e-1-300x250.gif

Proton: a positively charged particle

located in an atom’s nucleus

There are a lot of different ways to represent an atom

A

B

• What particle is labeled A? • What particle is labeled B?

http://titaniumphysicists.brachiolopemedia.com/wp-content/uploads/2017/08/c-atom_e-1-300x250.gif

This atom is “balanced”/“neutral”

What do you think

that means?

http://titaniumphysicists.brachiolopemedia.com/wp-content/uploads/2017/08/c-atom_e-1-300x250.gif

This atom is “balanced”/“neutral”

charges are balanced because protons and

electrons are balanced

"Electricity, Magnetism, & Electromagnetism Tutorial" Science Buddies. Science Buddies, 9 Aug. 2017. Web. 14 Oct. 2017 <https://www.sciencebuddies.org/science-fair-projects/references/electricity-magnetism-electromagnetism-tutorial?id=699>

Atoms aren’t always balanced. Sometimes they are more + or more -

http://willowwoodlessons.weebly.com/lesson-2---what-are-charges-and-how-do-they-behave1.html

The same is true for the objects those atoms make up. An object can have a bit of a charge if its atoms are

charged

Why do the balloons stick to the cat?

Why do the balloons stick to the cat? The cat and the balloons have opposite charges

Static Charge: a buildup of electric charge in an object caused by the presence of many particles with the same charge

Object B Object C

+ +

+

+ +

+ + -

-

-

-

-

Object A

+ +

+

+

+ -

-

- -

- -

Which objects have a static charge? How can you tell?

Positive Negative No static charge

+ +

+

+

+

+ +

+

+ +

+ + -

-

-

-

- -

-

- -

- -

Positive Negative No static charge

+ +

+

+

+

+ +

+

+ +

+ + -

-

-

-

- -

-

- -

- -

Notice that the “no charge” object still has +

and – particles….they just balance out

Atoms (and therefore objects) become charged because electrons move

Movement of electrons through a material = conduction

Dryer sheets contain positively-charged ingredients

that are heat activated.

static builds up when fabrics rub together and exchange electrons. Some surfaces get positively charged, and others get negatively charged, so they attract one another.

Static Charge can build up when….

• An uncharged material touches or comes near a charged material

• Certain types of uncharged materials contact each other

Charge by Contact: two uncharged objects touch and electrons move from one to the other

Rubber

+

+

+

-

Charge by Contact: two uncharged objects touch and electrons move from one to the other

Wool

+

+ + -

- - -

-

Charge by Contact depends a lot on the type of material • Some materials give up electrons easily, others don’t

Scientists have made lists based on experimentation of materials that tend to give or take electrons

Induction: static charging can occur without direct contact if one of the objects is already charged

Induction creates a temporary charge build up

Electrons still move.. But sometimes just within the object

“John Travoltage” simulation https://phet.colorado.edu/sims/html/john-travoltage/latest/john-travoltage_en.html

• What part of the simulation demonstrates charge by contact?

• What part of the simulation demonstrates induction?

Charge Polarization: build up of static charge when electrons change positions (but do not move between atoms)

The atoms line up so their – side faces the object that has a positive charge