physics

• Specific latent heat


  The amount of energy required to change the state of one kilogram of the substance with no change in temperature
• Energy change during state change

  1. Energy supplied

  2. Changes the energy stored

  3. But not the temperature
• Fusion


  • Change of state from solid to liquid
• Vaporisation


  • Change of state from liquid to gas
• Specific latent heat of fusion is 680,000 J/kg
• Gas pressure


  Collisions of particles with the container walls
• More frequent collisions


  Higher pressure
• Colliding with more force

  Higher average kinetic energy
• Q


  Current time
• Amps


  Unit of current
• The bigger the resistance


  The smaller the current for a given potential difference in the circuit
• Current through an ohmic conductor remains constant and is directly proportional to potential difference
• Resistance of a thermistor decreases as the temperature increases
• Series circuits


  • Current stays the same throughout each component
  • Potential difference is shared throughout each component
• Parallel circuits


  • Potential difference remains constant in each branch
  • Current splits
• Resistors in parallel


  Total resistance is less than the resistance of the smallest resistor
• Resistors in series


  Adding resistors increases the total resistance
• UK mains has 50 Hz - means it changes direction 50 times in a second
• Electrical appliances are connected through a 3-core cable - live wire (brown), neutral wire (blue), earth wire (green/yellow)