Unit 3 - Physics (The Characteristics of Electricity)

SNC1D Name: ______Date: ______

Electricity is a form of energy produced from a variety of sources. Think about all of the things that you do in a typical day...and think of how many of those things require electricity.

In this unit we will be studying... 1. ...static electricity [Chapter 11] 2. ...how electricity is generated and used and its effects on the environment [Chapter 12] 3. ...electrical currents and how they can be controlled and used. [Chapter 13]

Chapter 11 - Static Electricity

11.1 - What is Static Electricity?

Remember the structure of the atom from Chapter 6 in the Chemistry unit: -______(positive charge) & ______(no charge) are in the nucleus and do not move from one atom to another -______(negative charge) move in the space surrounding the nucleus, and can move from one atom to another

Objects are neutral when the number of protons = the number of electrons -if there are more electrons than protons, it is negatively-charged -if there are less electrons than protons, it is positively-charged.

Static electricity is an ______of electric charge on the surface of an object.

Law of Electric Charges: Charged objects exert an electric force: -objects with opposite charges ______each other ( + and - ) -objects with the same charge ______each other ( + and + or - and - )

If you bring a charged object toward a neutral one, it causes induced charge separation in the neutral object. The electrons in the neutral object move according to the law of electric charges and there is a force of attraction between the charged & neutral object.

A metal leaf electroscope can be used to detect charge. [See Figure 10, p.469]

There are many practical uses for static electricity: -electrostatic paint sprayers -electrostatic dusters & electrostatic precipitators [see 11.2] -laser printers [see 11.4] -photocopiers [see 11.6]

**Do questions #2-9 on page 471** 11.2 - Charging by Contact

There are different ways to charge an object: 1. charging by friction: -If you rub two objects together, ______will move from one object to another. The object that ______electrons gets a negative charge. The object that ______electrons gets a positive charge.

The electrostatic series [see Table 1, page 473] is a list of materials arranged in order of their tendency to gain electrons. When you rub two materials together, the material that is lower on the list will gain a negative charge because electrons will move onto it from the other material.

2. charging by conduction (direct contact): -If a negatively charged object touches a neutral object, some electrons will move from the negative object to the neutral object, giving the neutral object a ______charge. -If a positively charged object touches a neutral object, some electrons will move from the neutral object to the charged object, giving the neutral object a ______charge.

Grounding is connecting a charged object to a large body like the ______. It takes away the charge of the object by either adding electrons to or removing them from the Earth.

**Do questions #1,2,5,6 on page 477**

11.4 - Conductors & Insulators

Conductors are materials that ______the movement of electrons. e.g., metals, tap water, your body

Insulators are materials that ______or prevent the movement of electrons. e.g., plastic, wood, ebonite, glass, rubber **Do questions #1,6 on page 482**

11.6 - Charging by Induction

If you bring a charged object close to a neutral one (without contact), it causes electrons in the neutral object to move, resulting in an uneven charge distribution, causing a temporary charge. This is called charging by induction.

You can then charge an object permanently by induction by touching the charged object to the neutral one. [See Figure 3, page 487] **Do questions #2,6 on page 489**

11.8 - Electric Discharge

An electric discharge is the quick movement of electrons from one object to another. -for example: when you feel a shock when you touch someone or something; a ______bolt is also an electric discharge -lightning rods on buildings carry the electric discharge safely to the ground **Do questions #1,2 on page 495**