ELECTRICAL NATURE OF

MATTERSNC 1D

ELECTRICITY•Everything around you contains electric charges. You aren’t

aware of the charges until you make them move from their normal position.

•When these charges are forced to move the material has become “charged” with “electricity”.

STATIC ELECTRICITYAN IMBALANCE OF CHARGE ON

THE SURFACE OF AN OBJECT THAT STAYS IN THE SAME PLACE.

RECALL THE STRUCTURE OF THE ATOM…• Positive particles called _____________ and

neutral particles called ___________ are found inside the ________________. These particles do not move easily in and out of the nucleus.•  Negative particles called ______________ are

found in _________________ surrounding the nucleus. These particles can move from one atom to another.

ELECTRICAL CHARGES•  If an atom gains electrons it becomes

____________ charged. (There are more “” particles than “” particles)• If an atom loses electrons it becomes

_____________ charged.• (There are not enough “” particles)• If an atom has equal protons and

electrons it is ____________ .

• Electrical charges result from the movement of __________ and not from ______________ or ______________ .

CHARGING BY FRICTION

CHARGING BY FRICTION•Charging by friction

occurs when two different neutral objects are rubbed together and electrons are transferred from one object to another.

DETERMINING CHARGE• The object with the weakest hold on its

electrons transfers them to the other object and becomes positively charged.• The object with the stronger hold on its

electrons gains them from the other object and becomes negatively charged.•See page 473

PREDICT THE CHARGE…•When a rubber rod is rubbed with

Fur…Rubber has a stronger hold on its electrons and gains electrons from the furThis makes the rod negatively charged and the fur positively charged.

PREDICT THE CHARGE…•When a glass rod is rubbed with

silk…The silk has a ______________ hold on its electrons, becoming _____________ charged.The glass rod has a ____________ hold on its electrons becoming ______________ charged.

LAW OF ELECTRIC CHARGES

LAB ACTIVITY: YOU MOVE ME

YOU MOVE ME ACTIVITY

LAW OF ELECTRIC CHARGES•Like charges – repel•Unlike charges – attract•Charged objects attract neutral ones

INDUCED CHARGE SEPARATION•Neutral objects are attracted to

charged objects due to induced charge separation.•A shift in the position of

electrons in a neutral object when a charged object is brought near•Sometimes called polarizing the

molecules

DETECTING CHARGE•Scientists can detect the presence

of electric charges using an electroscope.• Pith ball electroscope – detects the

presence of a charge by moving towards a charged object.•Metal-leaf electroscope – detects

the presence of charge by causing the leaves to spread apart.

CHARGING BY CONTACT

CHARGING BY CONTACT•When two objects of different

charge are touched together, electrons are transferred from one object to the other. • This results in two objects

with the same charge.

CHARGING BY CONTACT•A charged object can only

charge a neutral object if:• the neutral object is a conductor

• if the neutral conductor is supported by an insulator

LET’S INVESTIGATE!

CHARGING POSITIVELY BY CONTACT

CHARGING NEGATIVELY BY CONTACT

THINGS TO REMEMBER…

•When charging by contact:• The objects must touch each other.• The objects will have the same charge.• The originally charged object will become a little less charged.

TIME TO WORK!• Page 471 # 4-9• Page 477 # 1, 2, 5, 6, 8

VAN DER GRAAF GENERATOR• A metal sphere is supported on an

acetate stand.• Inside a rubber belt turns against a

metal brush, charging the sphere by friction.• Static charge is transferred to you

when you touch the metal sphere.

CHARGING BY INDUCTION

CHARGING TEMPORARILY• A charged object is brought

next to but not touching a neutral object.• The electrons move either

towards or away from the charged object creating a temporary charge on one side of the neutral object.• Induced Charge Separation

CHARGING PERMANENTLY

CHARGING PERMANENTLY

TIME TO WORK!• Page 489 # 2, 3, 4, 6

INSULATORS AND CONDUCTORS •Conductors are materials that

allow electrons to move through them.• Insulators are materials that

inhibit or prevent the movement of electrons.•Resistors are a mixture made

up of conductors and insulators

GROUNDING• The excess charge on an object

can be removed by grounding the object.• Grounding involves connecting an

object to a large body, like Earth, that is capable of absorbing the charge and effectively remaining neutral itself.

Conductors Insulators

Resistors

USING PAGE 480-481…

TIME TO WORK!• Read pg 480-482 and answer

pg 482 # 2, 3, 6, 7• Read pg 492-495 and answer

pg 495 # 1, 2, 4