Resistance

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Resistance

• Chapter 19-2 Pages 700-707
• Physics

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Resistance IS FUTILE!!!So sayeth the Borg!
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Resistance

• I. Resistance the ratio of the potential
  difference across a conductor to the current it
  carries
• R ?V ? potential difference
• I ? current

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Resistance

• Resistance is measured in ohms (O)
• ? 1 O 1 Volt / Amp
• Ohms law the resistance is
• constant over a wide range
• of applied potential difference
• ?V / I constant

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Resistance

• Ohms law does not hold true for all materials
• - Materials that have a constant resistance over
  a wide range of potential differences are said to
  be ohmic.
• - Materials that do not function according to
  ohms law are said to be non-ohmic
• Diodes are common non-ohmic devices

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Resistance

• - Resistance depends on length, cross-sectional
  area, material, and temperature
• - Salt water and perspiration lower the bodys
  resistance.

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Resistance

• - Superconductors have no resistance below a
  critical temperature
• - Superconductor a material whose resistance is
  zero at or below some critical temperature which
  varies with each material

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Homework

• P. 703 1-5
• P. 707 1, 2, 4, 5, 7

• Make it so. Engage!