IGCSE物理试题解析

　　今天新航道小编就就带大家分析两道很有代表性的IGCSE物理试题，希望可以帮助大家了解一下什么样的解题思路才能达到考试局的要求吧。

　　IGCSE物理考试和体制内物理考试最 大的区别就是，它检测的知识面非常的广，但是难度并没有很高，其目的主要是为A-Level的物理学习打基础。

　　同时，IGCSE的考卷也不会出现国内所谓的超纲的问题，所以学生们面临的问题是记住大量的物理公式。不过还好，在IGCSE阶段我们还可以通过每个单元的实验来帮助记忆对应的公式。

　　IGCSE物理考三张试卷。参加核心课程内容考试的同学，考试卷1、试卷3和试卷5或6。参加拓展课程内容考试的同学，考试卷2、试卷4和试卷5或6。

　　IGCSE物理试题解析

　　题(2012年一月爱德思考试局IGCSE物理试题)

　　The isotope technetium-99 is a gamma emitter with a half-life of 6 hours. It is

　　used as a radioactive tracer in medicine.

　　The technetium-99 is injected into a patient’s bloodstream and carried around the body by the blood. The radiation it emits is detected outside the body.

　　Explain why technetium-99 is suitable for use as a tracer in this way.

　　(3 marks)

　　解题思路：

　　This question involves an application of radioactivity – the use of a radioactive isotope as a tracer.

　　Firstly, read the question without trying to answer it immediately.

　　首先，阅读题目后不要急着去回答问题。

　　Underline important pieces of information. I have underlined: gamma emitter, 6 hours.

　　标记出重要的信息，可以题目中标记了gamma emitter(伽马辐射源)、6 hours(6个小时)这两个重要信息。

　　Re-read the question.

　　再次阅读题目。

　　The question asks you to explain, and for this it s three marks.

　　这道IGCSE物理试题需要你对现象进行解释，并且给出了三分。

　　An explanation is the setting out of purposes and reasons for a decision or phenomenon, in this case, the use of a specific isotope as a radioactive tracer.

　　To gain three marks we need three reasons.

　　为了获得三分，我们需要答出三个要点。

　　These can be, in some cases, inferred from the question. For example, the question says, “ The radiation it emits is detected outside the body.”

　　From this we know the first point: The radiation released must be able to exit the body; Technetium-99 is a gamma emitter, allowing penetration through and outside of the body.

　　Further points can be similarly earned: the question tells us that this isotope has a six-hour half-life.

　　The second point is therefore that this half-life is sufficient to allow the tracer to be carried around the body by the bloodstream and to achieve its purpose in being used as a tracer.

　　The third point is that this half-life is low enough that the activity falls to low levels after use, ensuring patient safety.

　　These points can be presented in different forms, both as full sentences and as bullet points.

　　以上三点可以用各种形式展现出来，可以是句子，也可以是要点。

　　第二题

　　A student investigates how the resistance of a wire depends on its length.

　　The photograph shows the circuit that the student uses.

　　(a) Draw a circuit diagram to show how the components in the photograph are connected.(3)

　　(b) (i) Complete the table by naming the key variables in this investigation.(1)

　　(ii) Describe the method the student should use for this investigation.(5)

　　解题思路：

　　Part A is relatively straightforward; it requires the student to see the above photograph and to reproduce it in the style of a circuit diagram, which they should be very familiar with drawing (voltmeter in parallel, ammeter in series).

　　Part A比较简单; 学生只需要将图片上的内容以电路图的方式画出来即可，考生需要非常熟悉绘图(电压表并联，电流表串联)。

　　The second part is more interesting; it expects the student to produce an experimental design and, generously, provides some organisation in first identifying the variables.

　　第二部分就显得有趣多了，题目要求学生根据部分提供的变量做一个实验设计。

　　The independent variable is the one that you, the scientist, control and vary as you conduct the experiment. In this case the length of the wire.

　　The dependent variable is the one that depends upon the independent variable; we measure this one to determine how it changes as we change the independent variable.In this case, the resistance - determined by measurements of current and voltage.

　　For five marks you must then describe the experiment:

　　题目共5分，所以必须要描述这个实验。

　　The first point is to set up the apparatus as shown in the diagram.

　　Having determined the variables earlier in the question, the second step is to write down how you will measure these. The independent variable will be controlled by adjusting the position of the crocodile clip on the wire (see photograph) and will be measured with the ruler. The dependent variable will be measured by taking readings from the voltmeter and ammeter at a given length of wire and using the equation V = IR to determine resistance. Further readings are then taken at different lengths of wire.The next point is to mention repeat measurements, taking an average.

　　Experimental accuracy should be considered. Following the scientific method, other factors that may affect the result must be controlled. In this instance temperature would have a significant effect. The wires should, therefore, be disconnected between readings to avoid them heating up, which would change the readings. The voltmeter and ammeter should also be checked for zero errors (there should be 0 current when no power supplied).

　　Five marks could be achieved by mentioning fewer points than listed here.

　　In summary:

　　总结：

　　1. Determine variables

　　确定变量

　　2. Describe the experimental set-up and how variables will be measured

　　描述实验设置以及变量的测量

　　3. Consider experimental accuracy, variables to control and how they will be

　　controlled

　　考虑实验准确性，控制变量以及如何控制

　　2道IGCSE物理试题就分析到这里，大家有觉得对IGCSE物理更了解了一点吗?

　　最后提醒一下今年的GCSE/IGCSE学生，英国本土大考虽然取消了，但国际考试还没有。而且今年英国的打分方案和去年不同，教师评估分都是需要“证据”支持的，包括但不限于平时作业、测试、模考、外部试卷等考察。所以，大家不仅要保持和大考正常开考时一样的学习状态，也要有意识地提高自己的平时成绩。