(a) The diagram shows the energy transformations in a fuel burning power station.
(i) Name one fuel that is burned to provide the energy source for a power station.
(ii) Use the diagram and an appropriate equation to calculate the efficiency of the power station.
Show clearly how you work out your answer.
Efficiency = ........................................
(iii) Name the process by which a nuclear fuel provides the energy needed to generate electricity in a nuclear power station.
(b) Electricity is distributed from power stations to consumers along the National Grid.
(i) Transformers are part of the National Grid. Transformers are efficient devices.
What is meant by a device being efficient ?
(ii) When electricity flows through a cable, some energy is transformed into heat. Explain how the National Grid system reduces the amount of energy lost as heat.
(c) Read this information taken from a recent newspaper article.
- Researchers have found that children living close to overhead power cables are more likely to develop leukaemia.
- The researchers studied two groups of children. One group had developed leukaemia, the other group was healthy.
- Although the researchers found a link, they are unable to explain why it happened. They say that the results may have happened by chance.
- Other factors that have not been investigated, such as the environment, the geographical area or the children’s genes, could be important.
- A cancer research charity said that childhood leukaemia was most likely to be caused by factors that parents were unable to control.
(i) Why did the researchers study a group of healthy children?
(ii) The information does not say how many children were studied.
Why should this data have been included in the article?
(iii) The researchers could not be certain that the overhead power cables were responsible for the increased chance of children developing leukaemia.
(iv) The results of the research carried out by scientists may worry some people. What do you think scientists should do? Put a tick beside your choice of statement:
Scientists should publish their research findings straight away.
Scientists should not publish their research findings until they have found out as many facts as possible.
Give a reason for your choice.
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From Q1 P1 AQA January 2008 (Higher)