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Voltage

Objectives:

  • Identify the six most common voltage sources.
  • Describe six different methods of producing electricity.
  • Define a cell and a battery.
  • Describe the difference between primary and secondary cells.
  • Describe how cells and batteries are rated.
  • Identify ways to connect cells or batteries to increase current or voltage output or both.
  • Define voltage rise and voltage drop.
  • Identify the two types of grounds associated with electrical circuits.

Voltage Sources​

  • Friction
  • Magnetism
  • Chemicals
  • Light
  • Heat
  • Pressure

Friction​

The triboelectric effect is the phenomenon where certain materials become electrically charged after they come into frictional contact with a different material.

How it works step by step:

  1. Contact - When two different materials touch, some electrons may be transferred from one material to the other.
  2. Separation - When the materials are pulled apart, one material ends up with extra electrons (negatively charged), and the other ends up with too few electrons (positively charged).
  3. Static charge - This difference in charge creates static electricity, which can remain until the charges either discharge or slowly leak away.
note

Rubbing a balloon on your hair.

  • Hair loses electrons and becomes positively charged.
  • the balloon gains the electrons and becomes negatively charged.
  • When you bring the negatively charged balloon close to the wall, the negative charges on the balloon repel the free-moving electrons on the surface of the wall.
  • The side of the wall closest to the balloon is now left with a slight excess of positively charged protons. Even though the wall as a whole is still neutral.
  • Finally, the negatively charged ballon is now attracted to the newly created positively charged surface on the wall.

Triboelectric Series​

  • Some materials "like" to give away electrons (becoming positive).
  • Others "like" to take electrons (becoming negative).

Triboelectric series is a list of materials ranked by their tendency to gain or lose electrons.

triboelectric series rank

Magnetism​

  • The most common method of producing electrical energy.
  • Produced using generator powered by steam from nuclear power or coal, water, wind, or gasoline...

Chemical​

  • The second most popular method of producing electrical energy.

Light​

  • Photovoltaic cell
  • A single cell can produce a small voltage.
  • Many cells must be linked to produce a usable voltage and current.