Electricity

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Electricity

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What is electricity?

• --- All the phenomena caused by positive and
  negative charges ---

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Electric Charges

• The electric charge is a property of protons and
  electrons. A proton is positively charged, and an
  electron is negatively charged.

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Electric Charges

• A negatively charged object has a surplus of
  electrons (more electrons than protons)

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Electric Charges

• A positively charged object has a deficit of
  electrons (fewer electrons than protons)

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Electrical charges

• Proton ? charge
• Electron ? - charge
• A negatively charged body contains more electrons
  than protons.
• A positively charged body contains fewer
  electrons than protons.

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Forces of Attraction and Repulsion

• Similar electric charges (two positive charges or
  two negative charges) repel each other
• Opposite electric charges (one positive and one
  negative charge) attract each other

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Forces of Attraction and Repulsion

• electric force- force that permits the attraction
  or repulsion between charges
• law of conservation of charge- electric charges
  can not be created nor destroyed they can only
  be transferred from one object to another

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• Most objects are electrically neutral equal
  numbers of positive and negative charges (protons
  and electrons)
• We can however give a charge to an object by
  transferring electrons from one place to another
  (electrification).

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Electroscope
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Conductors and Insulators

• Conductors
• a substance that permits charges to circulate
  freely
• Ex metals, electrolytic solutions

• Insulators
• a substance that does not permit charges to
  circulate freely
• Ex wood, plastic, glass, paper, ceramic, rubber,
  silk, air

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Semi-conductors

• conductibility depends on different factors
• Often used in electronics
• Ex carbon, metalloids

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Static Electricity

• phenomena linked to charges at rest

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Charging by Rubbing

• When two objects are rubbed together, certain
  atoms from one take the valence electrons of the
  other. This results in two charged objects with
  opposite signs.

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Charging by Rubbing
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Charging by Conduction

• charge an object by placing it in contact with
  another object that is already charged. The
  charges are shared between the two objects. The
  result is two charged objects with the same sign
  but the charge is weaker than in the original
  object.

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Charging By Induction

• action that occurs without direct contact
• charged object comes close to a neutral object,
  without touching it
• charges with opposite signs progressively
  accumulate on the side close to the charged
  object. At the same time, if the second object is
  a conductor, an equal number of opposite charges
  accumulates on the other side of the object,
  conforming to the law of conservation of charge.

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Charging By Induction
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