How does the resistance change?

• With Current

  • current increases, electrons has more energy
  • when electrons flow through a resistor, they collide with the atoms in the resistor
  • this transfers energy to the atoms, causing them to vibrate more
  • makes it more difficult for electrons to flow through the resistor
  • resistance increases, current decreases
• With Temperature

  • Normal wires, same process occurs as atoms vibrate when hot
  • Thermistor, in hotter temperatures the resistance is lower. these are often used in temperature detectors/thermostats
• With Length

  • greater the length, the more resistance and lower the current
  • electrons have to make their way through more resistor atoms, so it is harder than using a shorter wire
• With Light

  • LDR
  • Greater the intensity of light, lower the resistance
  • resistance is greatest when dark
  • used in automatic night lights
• With Voltage

  • Diodes
  • -allows current to flow freely in one direction
  • in opposite direction, very high resistance so no current an flow