Transcript Section 1 Electrical Charge and Force Chapter 16 - Ms

Chapter 16
Section 1 Electrical Charge and
Force
Objectives
• Indicate which pairs of charges will repel and which
will attract.
• Explain what factors affect the strength of the electric
force.
• Describe the characteristics of the electric field due
to a charge.
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Chapter 16
Section 1 Electrical Charge and
Force
Bellringer
1. Static electricity is a part of life. Can you name at least
five examples of static electricity that occur in your
home?
2. Fabric softeners are commonly used today because
they eliminate static cling.
3. Explain why clothes in the dryer get static cling.
4. Why can walking across a carpeted room be a
shocking experience?
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Chapter 16
Section 1 Electrical Charge and
Force
Electric Charge
• Electric charge is an electrical property of matter
that creates electric and magnetic forces and
interactions.
• Like charges repel, and opposite charges attract.
• The two types of charges are called positive and
negative.
• An object’s electric charge depends on the imbalance
of its protons and electrons.
• Electrons are negatively charged, protons are
positively charged, and neutrons are neutral (no
charge).
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Chapter 16
Section 1 Electrical Charge and
Force
Electric Charge, continued
• Negatively charged objects have more electrons
than protons.
• Positively charged objects have fewer electrons
than protons.
• The SI unit of electric charge is the coulomb, C.
• A proton has a charge of 1.6  10–19 C
• An electron has a charge of 1.6  10–19 C.
• The net electric charge of a charged object is
always a multiple of 1.6  10–19 C.
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Chapter 16
Section 1 Electrical Charge and
Force
Electric Charge, continued
• Conductors allow charges to flow; insulators do not.
• An electrical conductor is a material in which charges can
move freely and that can carry an electric current.
• An electrical insulator is a material that does not transfer
current easily.
• Objects can be charged by the transfer of electrons.
• The outermost electrons can be easily transferred from one
atom to another.
• Charging by friction is when one material gains electrons
and becomes negatively charged, and the other loses
electrons and becomes positively charged.
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Chapter 16
Section 1 Electrical Charge and
Force
Charging by Contact
When a negative rod touches a
neutral doorknob, electrons move
from the rod to the doorknob.
The transfer of electrons to
the metal doorknob gives
the doorknob a net negative
charge.
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Chapter 16
Section 1 Electrical Charge and
Force
Induced Charges
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Chapter 16
Section 1 Electrical Charge and
Force
Electric Force
• Electric force is the force of attraction or repulsion
between objects due to charge.
• The electric force at the atomic and molecular level is
responsible for most of the common forces we can
observe.
• The electric force is also responsible for effects that we
can’t see.
• Electric force depends on charge and distance.
• The electric force between two objects is proportional
to the product of the charges on the objects.
• The electric force is inversely proportional to the
square of the distance between two objects.
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Chapter 16
Section 1 Electrical Charge and
Force
Electric Force, continued
• Electric force acts through a field.
• An electric field is a region in space around a
charged object that causes a stationary charged
object to experience an electric force.
• One way to show an electric field is by drawing
electric field lines.
• Electric field lines point in the direction of the
electric force on a positive charge.
• The electric field lines around a positive charge point
outward.
• The electric field lines around a negative charge point
inward.
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Chapter 16
Section 1 Electrical Charge and
Force
Electric Field Lines
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Chapter 16
Section 1 Electrical Charge and
Force
Electric Field Lines
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Chapter 16
Section 1 Electrical Charge and
Force
Electric Force, continued
• Electric field lines never cross one another.
• Field lines show both the direction of an electric
field and the relative strength due to a given
charge.
• More lines are drawn for greater charges to
indicate greater force.
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