resistance + ohms law

• resistance - the property of a material that slows down the flow of electrons and converts electrical energy into other forms of energy; measured in ohms
• resistor - an electrical component that has a specific resistance
• factors that affect the amount of resistance in materials

  • length of material that the current passes through - longer = more resistance
  • cross-sectional area is inversely proportional to the resistance - thinner = more resistance
  • type of material the current passes through - the material's resistivity
• voltage is directly proportional to current

  • if you increase the voltage connected to a circuit, the current will also increase
• resistance and current are inversely proportional

  • if you increase the resistance in a circuit, the current will decrease
• short circuit - a circuit with a resistance that is too low, making the current so high that it is dangerous
• electrical resistance - ratio of the voltage to the current
• ohm - unit of measurement for resistance
• ohm's law - voltage = current x resistance
• units of measurement for ohm's law

  • voltage = volts
  • resistance = ohms
  • current = amps
• prefixes

  • milli (m) represents 1/1000
  • kilo (k) represents 1000
  • mega (M) represents 1000000
• ways to determine resistance

  • experimentally - measure the voltage and the current through a load; use ohm's law to calculate
  • use an ohmmeter to measure resistance directly