What is an electric charge?

1
What is an electric charge?

• An electric charge is the electrical property of
  matter that creates a force between objects.
• the attracting or repelling behavior of a
  material.

2
What is an electric charge?

• To create this charge, electrons must move from
  one atom to another.

3
What is an electric charge?

• All matter is made up of atoms
• Atoms are made up of smaller particles called
  protons, neutrons and electrons.

4
Why do objects become charged?

• An imbalance of its protons and electrons occurs
• Protons positive
• Neutrons neutral
• Electrons negative

In the nucleus
Orbits the nucleus
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Conservation of Charge

• Electrons are bound more tightly to some atoms
  and molecules than others. When an electron is
  transferred, it creates an ion.

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Conservation of Charge

• A charged atom is an ion.
• positive ion atom loses electrons
• negative ion atom gains electrons
• Charge is always conserved never created or
  destroyed!

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ELECTRICAL CONDUCTORS

• Conductors allow electrons to flow
• Conductivity depends upon how tightly the atom
  holds on to its electrons.
• loose electrons in a material conduct the
  electric charge through (metals).
• Examples of conductors Metal, graphite, etc.

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In solid conductors, the electrons carry the
charge through the circuit because they are
loosely held. In fluids, like those in a car
battery, positive and negative ions and electrons
may compose the flow of electric charge.
ELECTRICAL CONDUCTORS
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ELECTRICAL INSULATORS

• Insulators DO NOT conduct electricity well!!
  They provide RESISTANCE to the flow of electrons.
• RESISTANCE IS CAUSED BY INTERNAL FRICTION
• Examples of Insulators Glass, wood, rubber, etc.

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SEMICONDUCTORS

• Semiconductor material made to behave sometimes
  as insulators and sometimes as conductors
  (germanium and silicon).

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How can objects become charged?

• Charging by Contact
• Two objects are rubbed against each other and
  electrons are transferred.
• PROTONS NEVER MOVE from one atom to another.

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How can objects become charged?

• A charged object touches a neutral object,
  transferring electrons
• PROTONS NEVER MOVE from one atom to another

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How can objects become charged?

• Charging by Induction (charging at a distance)
  A charged object is held near a neutral object
  and causes an overall charge.

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Charge Polarization

• When charges rearrange in an atom, one side
  becomes slightly more positive and the other side
  becomes slightly more negative. The atom is
  electrically polarized. Ex charged comb
  attracting bits of paper or charged balloon
  sticking to the wall.

15
Electric Fields

• An electric field surrounds every electric charge
  and exerts the force that causes other electric
  charges to be repelled or attracted.
• Electric fields are represented by arrows that
  show how the electric field would make a positive
  charge move.

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Charges Exert Forces
Unlike charges attract each other (positive and
negative) Like charges repel each other
(positive to positive or negative to negative)
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Charges Exert Forces

• Just like gravity, the amount of electrical force
  exerted on an object is related to the following
• Distance from the charged object
• Strength of the charge on the charged object

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What is an electric charge?

• Protons are positive and are found in the nucleus
  of the atom
• Neutrons are neutral and found in the nucleus of
  the atom
• Electrons are negative and are found in regions
  around the outer edges of the atom