Resistance

    Cards (7)

    • The formula for resistance is: Resistance (Ω)=Resis\tan ce\ (Ω)=VoltageCurrent =\frac{Voltage}{Current}\ = VI\ \frac{V}{I}
    • Factors affecting resistance:
      • length
      • cross-sectional area
      • material
    • Length is proportional to resistance because the electrons have to travel a longer length, and thus encounter more resistance: ΩLΩ∝L
    • Resistance is proportional to cross-sectional area because more electrons can flow per unit time, increasing the current and therefore decreasing the resistance: Ω  1AΩ\ ∝\ \frac{1}{A}
    • Resistance is related to the material because a better conducting material has less resistance
    • Current Voltage Character of an Ohmic Resistor and a Filament Lamp
    • Ohm’s law states that voltage across a resistor is directly proportional to the current through it. This is only true if the temperature of the resistor or lamp remains constant
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