Behaviors of Resistors

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Behaviors of Resistors

• Students will
• Calculate resistance, current, and potential
  difference using the definition of resistance.
• Distinguish between ohmic and non-ohmic
  materials.
• Know what factors affect resistance.
• Describe what is unique about superconductors.

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Behaviors of Resistors
Resistance (R) the opposition to the flow of
current in a conductor. (ohm O)
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Behaviors of Resistors
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Behaviors of Resistors
If resistance is constant over a range of
potential differences, it obeys Ohms Law. (ohmic)
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Behaviors of Resistors
Ohms law does not hold for all materials.
(non-ohmic)
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Behaviors of Resistors
Resistance depends on length, cross-sectional
area, material, and temperature.
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Factors That Affect Resistance
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Behaviors of Resistors
The resistance of a steam iron is 19.0 O. What is
the current in the iron when it is connected
across a potential difference of 120 V?
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Behaviors of Resistors
Given R 19.0 O ?V 120 V Unknown I ?
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Resistance Problemspage 703 1-6
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Resistance Problemspage 703 1-6
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Behaviors of Resistors
Salt water and perspiration lower the bodys
resistance. The carbon microphone uses varying
resistance.
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Behaviors of Resistors
Superconductors a material whose resistance is
zero at or below some critical temperature, which
varies with each material
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Behaviors of Resistors