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SOL 4.3 -- Electricity

Key concepts:

  1. electricity flows easily through conductors but not insulators;
  2. electricity flows through closed circuits;
  3. static electricity can be generated by rubbing certain materials together;
  4. electrical energy can be transformed into radiant, mechanical, and thermal energy;
  5. a current flowing through a wire creates a magnetic field.
CIRCUITS
  • A continuous flow of negative charges (electrons) creates an electric current.
  • The pathway taken by an electric current is a circuit.

  • Closed circuits allow the movement of electrical energy.
  • Open circuits prevent the movement of electrical energy.
  • In a series circuit, there is only one pathway for the current, but in a parallel circuit there are two or more pathways for it.
CONDUCTORS AND INSULATORS
  • Electrical energy moves through materials that are conductors (metals). Insulators (rubber, plastic, wood) do not conduct electricity well.
  • Among conducting materials, the rate at which energy flows depends on the material’s resistance.
STATIC ELECTRICITY
  • Rubbing certain materials together creates static electricity.
  • Lightning is the discharge of static electricity in the atmosphere.
ENERGY TRANSFORMATIONS
Electrical to
Mechanical (motion)		 Electrical to
Light (radiant)		 Electrical to
Thermal (heat)
ENERGY TRANSFORMATIONS
  • Electrical energy can be transformed into light or motion, and can produce thermal energy.
  • describe the types of energies (i.e., thermal, radiant, and mechanical) that are transformed by various household appliances (e.g., lamp, toaster, fan).
MAGNETIC FIELDS
  • Certain iron-bearing metals attract other such metals (also nickel and cobalt).
  • Lines of force extend from the poles of a magnet in an arched pattern defining the area over which magnetic force is exerted.
  • An electric current creates a magnetic field.
  • A  moving magnetic field creates an electric current.
  • A current flowing through a wire creates a magnetic field.
  • Wrapping a wire around certain iron-bearing metals (iron nail) and creating a closed circuit is an example of a simple electromagnet.
HISTORICAL CONTRIBUTIONS
  • Benjamin Franklin, Michael Faraday, and Thomas Edison made important discoveries about electricity.     
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