• Resistance is defined as the?opposition?to current
  • For a given potential difference:?The higher the resistance the lower the current
• Wires are often made from copper because copper has a low electrical resistance. This is also known as a good conductor
• The resistance?R?of a conductor is defined as the ratio of the potential difference?V?across to the current?I?in it

Resistance of a component is the ratio of the potential difference and current

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• Resistance is measured in?Ohms (Ω)
• An Ohm is defined as one volt per ampere
• The resistance controls the size of the current in a circuit
  • A?higher?resistance means a?smaller?current
  • A?lower?resistance means a?larger?current
• All electrical components, including wires, have some value of resistance

Determining Resistance

• To find the resistance of a component, we can set up a circuit like the one shown below

A circuit to determine the resistance of a component

• The power supply should be set to a low voltage to avoid heating the component, typically 1-2 V
• Measurements of the potential difference and current should then be taken from the voltmeter and ammeter respectively
• Finally, these readings should be substituted into the resistance equation