AQA GCSE Science - Lagan College Physics



1 |A television is designed to transfer electrical energy into light and sound energy. Some energy is transferred to the surroundings, which become warmer. |3 | | |

| 2 |a kinetic energy, sound |2 | |

| |b Sound. |1 | |

| |c B It eventually makes the surroundings warmer. |1 | |

| |d It is less efficient. |1 | |

| 3 |a Efficiency |4 | |

| |= [pic] | | |

| |Efficiency = [pic] | | |

| |Efficiency = 0.90 x100% | | |

| |Efficiency = 90% | | |

| | | | |

| |b The energy becomes too spread out to use. | | |

| |c The insulation reduces the rate at which energy is lost from the tank to the surroundings. | | |

| |The water in the tank will stay hotter for longer. | | |

| |This increases the efficiency of the hot water system. | | |

| | |1 | |

| | |3 | |

| 4 |a Gravitational potential energy. |1 | |

| |b Efficiency |4 | |

| |= [pic] | | |

| | | | |

| |total energy supplied = [pic] | | |

| |total energy supplied = 600 000 J | | |

| |energy wasted = 600 000 J − 240 000 J | | |

| |energy wasted = 360 000 J | | |

| |c Friction between the moving parts of the motor causes some energy to be transferred by heating. | | |

| |(Or the current flowing in the motor has a heating effect.) | | |

| | |2 | |

| 5 | [pic] |3 | |

| | | | |

| |There is a clear, balanced and detailed description of why an electric heater is the only appliance that can | | |

| |possibly be100% efficient. The answer shows almost faultless spelling, | | |

| |punctuation and grammar. It is coherent and in an organised, logical sequence. It contains a range of appropriate | | |

| |or relevant specialist terms used accurately. | | |

| | | | |

|6 |There is a partial description of why an electric heater is the only appliance that can possibly be 100% efficient.|5-6 | |

| |There are some errors in spelling, punctuation and grammar. The answer has some structure and organisation. The use| | |

| |of specialist terms has been attempted, but not always accurately. | | |

| | | | |

| | | | |

| |There is a brief description of why an electric heater is the only appliance that can possibly be 100% efficient,| | |

| |which has little clarity and detail. The spelling, punctuation and grammar are very weak. The answer is poorly |3-4 | |

| |organised with almost no specialist terms and/or their use demonstrating a general lack of understanding of their | | |

| |meaning. | | |

| | | | |

| |No relevant content. | | |

| | | | |

| |Examples of physics points made in the response: |1-2 | |

| |• all electrical devices convert some energy by heating. | | |

| |• in most appliances some energy is wasted. | | |

| |• energy is usually wasted by heating. | | |

| |• the useful energy transfer in the heater is by heating. | | |

| |• an appliance is 100% efficient only if all the energy transfer is useful. | | |

| |• the heater can be 100% efficient if no energy is wasted as light. |0 | |

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P1, Chapter 2

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