Electricity—ChapterElectricity—Chapter 7 7

IPC-- Mrs. ZagalaIPC-- Mrs. Zagala

IPC Chapter 7: Electricity

Section 1: Electric Charge

*Electric Charges

ex: rubbing shoes on carpet

*All objects have both positive and negative charges

(p and e)

*Static Electricity-the accumulation of excess electric charges on an

object

fig. 2 (pg. 95)

Electricity (cont’d.) section 1Electricity (cont’d.) section 1

Law of Conservation of Law of Conservation of ChargeCharge

-charge can be transferred -charge can be transferred from object to object, but cannot from object to object, but cannot be created or destroyedbe created or destroyed

Electricity (section 1 cont’dElectricity (section 1 cont’d))

Electrically charged objects Electrically charged objects obey two rules:obey two rules: Opposite charges attractOpposite charges attract Like charges repelLike charges repel

(similar to two ends of a magnet)(similar to two ends of a magnet) (clothes out of the dryer ex)(clothes out of the dryer ex)

Electricity (section 1 cont’d)Electricity (section 1 cont’d)

Force at a Distance:Force at a Distance: An An electric fieldelectric field surrounds every surrounds every

electric chargeelectric charge The electric field exerts the force The electric field exerts the force

that causes other electric charges that causes other electric charges to moveto move

ex:ex: tissue paper sticks to a tissue paper sticks to a charged ballooncharged balloon

Conductors and InsulatorsConductors and Insulators

ConductorsConductors—materials through —materials through which electrons can move more which electrons can move more easilyeasily Ex: skin, metals, etc.Ex: skin, metals, etc.

InsulatorsInsulators—a material that —a material that doesn’t allow electrons to move doesn’t allow electrons to move through it easilythrough it easily

Transferring Electric ChargeTransferring Electric Charge( 2 different methods( 2 different methods))

Charging by contactCharging by contact:: The process of transferring charge The process of transferring charge

by touching or rubbingby touching or rubbing

Charging by inductionCharging by induction::

* The rearrangement of electrons on * The rearrangement of electrons on a neutral object caused by a a neutral object caused by a nearby charged objectnearby charged object

(fig. 7 pg 198)(fig. 7 pg 198)

How Lightning OccursHow Lightning Occurs

Lightning Lightning is a large static is a large static dischargedischarge (a transfer of charge through the (a transfer of charge through the

air between two objects because air between two objects because of a buildup of static electricity)of a buildup of static electricity)

As air masses move in a As air masses move in a thundercloud, areas of positive thundercloud, areas of positive and negative charge build upand negative charge build up

Eventually, a discharge occurs Eventually, a discharge occurs between the cloud and the groundbetween the cloud and the ground

((More on LightningMore on Lightning))

As the electric charges move As the electric charges move through air, they collide with through air, they collide with atoms and moleculesatoms and molecules

These collisions cause atoms These collisions cause atoms and molecules in air to emit light and molecules in air to emit light (sparks we see)(sparks we see)

ThunderThunder

Thunder is powerful sound Thunder is powerful sound waves produced by lightningwaves produced by lightning

Heat produced by electrical Heat produced by electrical energy in a lighting bolt cause energy in a lighting bolt cause air to expand rapidly producing air to expand rapidly producing sound waves you hear as sound waves you hear as thunderthunder Pg. 199Pg. 199

GroundingGrounding

Providing a path for charge to Providing a path for charge to reach earth is called reach earth is called groundinggrounding

Grounding Grounding is important to is important to protect objects on Earth from protect objects on Earth from lightning damage lightning damage Ex: metal lightning rod, faucets, Ex: metal lightning rod, faucets,

sinks, pipes, etc.sinks, pipes, etc.

Detecting Electric ChargeDetecting Electric Charge

ElectroscopeElectroscope—an instrument —an instrument used to detect the presence of used to detect the presence of electric chargeselectric charges

made up of two thin, metal made up of two thin, metal leaves attached to a metal rod leaves attached to a metal rod w/a knob at the topw/a knob at the top

**Fig. 10/pg. 201**Fig. 10/pg. 201