3 Electricity

• How does resistance decrease as temperature increases

  • Increase in temp, increases energy transfer to lattice ions
  • Increase in charge carriers
  • from I = nqvA, increase in charge carriers increases current
  • so V= IR increase current decrease in resistance
• Explain why resistance decreases as temperature increases

  • Number of conduction electrons increase
  • So current will increase (R = V/I)
• V1 = ( R1 / R1 + R2 ) x V2
• P = IV
• V = IR
• Explain how the resistance of the LDR changes as the light level increases

  As light levels increase, electrons become more free

  so the resistance of LDR decreases