Cards (15)

    • what factors affect the energy transferred when charge flows through a component?
      • amount of charge
      • potential difference across the component
    • define potential difference in terms of charge
      the work done per unit charge
    • when an electrical current flows through a resistor why does it heat up?
      • collisions between electrons and the ions in the resistors lattice
      • causes a transfer of kinetic energy into thermal energy
      • dissipated to the surroundings
    • give an equation relating potential difference to charge
      E = QV
      • energy transferred = charge x P.D
    • give an equation linking energy, current and potential difference
      E = ITV
      • energy = P.D x current x time
    • how do low resistance wires reduce unwanted energy transfers?
      • smaller resistance will mean there are fewer collisions
      • therefore less energy will be wastes through heating
    • what are some advantages of the heating effect
      • useful for appliances such as toasters or electrical fires
      • where the heat is the desired product
    • what are some disadvantages of the heating effect
      • loss of energy as heat energy can make an appliance inefficient
      • if an appliance overheats: could ruin device/ injure the user
    • define power
      the rate of energy transfer, or the rate of which work is done
    • the energy transferred per second is also known as...

      power
    • what are the units of power?

      watts, W
    • give an equation linking power and potential difference
      power = current x p.d
    • give an equation to work out power without p.d 

      P = I2RI^2R
    • give an equation linking power and energy
      power = energy/time
    • give equations linking power and resistance
      • P = I2RI^2R, power = current2^2 x resistance
      • P = V2÷RV^2\div R, power = p.d2^2÷\divR