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A-level物理 | Paper 5 如何在实验设计问题上拿到高分?

【丰老师】  2019-05-15 发布

A-level物理Paper 5 Planning , Analysis and Evaluation的考试时间为1小时15分钟,共计2题,分值分别为15分。本篇文章将对学生棘手的实验设计题进行分析,帮助广大考生们在Paper5得到一个优异的成绩。

对于A-level物理想要拿A的同学来说,这30分至关重要。


我们先来分析下这15分的得分是如何分布的:

1)Defining the problem,3分;

2)Methods of data collection,5分;

3)Method of analysis,2分;

4)Safety considerations,1分;

5)Additional detail,4分。

因此我们只需要按分答题即可拿到这15分。


第一部分Defining the problem中,这3分分别对应定义independent variable、dependent variable以及控制其他变量。

第二部分Methods of data collection则跟具体题目有关,对于能得分的点是:label diagram、表明自变量如何测量、表明应变量如何测量、重复实验采用取平均值得方法来获取数值,以及如何才能得到实验需要的值。

第三部分Method of analysis则相对简单,我们要表明所画的graph的横轴与纵轴所对应的值,和实验想要求的值的表达式(跟斜率与截距有关)。

第四部分Safety considerations的1分也与具体实验内容有关,一般用“precaution linked to…”来回答。

第五部分Additional detail则更为开放,可对测量方法进行补充,也可以对安全问题进行补充,并且数据分析这块的补充肯定是“Relationship is valid if the graph is a straight line passing through the origin or having a y-intercept”。

至此,我们来结合实际题目来应用下上述提到的方法。


A student is investigating simple harmonic motion using an electric vibrator. A plate is attached to the top of the electric vibrator. A small mass is placed on the metal plate as shown in Fig. 1.1.

1111.png
 

An alternating potential difference (p.d.) is applied to the vibrator. For a given peak p.d. , there is a maximum frequency at which the small mass remains in contact with the plate. The contact between the small mass and plate is lost when the frequency is greater than.

It is suggested that the relationship between and is222.pngwhere k is a constant.

Design a laboratory experiment to test the relationship between and.


首先我们先完成Defining the problem的3分:1)V is the independent variable; 2) f is the dependent variable; 3) keep the position of the mass constant.

其次完成Methods of data collection的5个点:1)labelled diagram showing signal generator connected to vibrator with two wires with mass on plate; 2) voltmeter connected in parallel with vibrator in a workable circuit; 3) measure f from signal generator; 4) detail regarding mass leaving the plate; 5) repeat each experiment for the same value of V.

Method of analysis的2分较为简单:1)plot a graph of f2 against 1/V; 2) k = gradient 关于Safety 我们可以指出:precaution linked to mass leaving vibrating plate

最后我们补充4点内容作为Additional detail:1)先写上万用句:relationship is valid if the graph is a straight line passing through the origin; 2) wait for vibrator to oscillate evenly; 3) method to determine period of oscillation from c.r.o; 4) clean surfaces of metal plate.


根据上述的真题分析,运用我们讲解过的方法便顺利完成了这道题目。可能有的学生无法完成拿到15分的分值,那么应用上述解题思路,失分点就控制在Methods of data collection以及最后的Additional detail这两块中。由于几个点没有踩到给分点而导致错误,那么也能保证在10分以上的成绩。对于我们Paper5拿20以上的目标也有了良好的保障。

r with two wires with mass on plate; 2) voltmeter connected in parallel with vibrator in a workable circuit; 3) measure f from signal generator; 4) detail regarding mass leaving the plate; 5) repeat each experiment for the same value of V.

Method of analysis的2分较为简单:1)plot a graph of f2 against 1/V; 2) k = gradient 关于Safety 我们可以指出:precaution linked to mass leaving vibrating plate

最后我们补充4点内容作为Additional detail:1)先写上万用句:relationship is valid if the graph is a straight line passing through the origin; 2) wait for vibrator to oscillate evenly; 3) method to determine period of oscillation from c.r.o; 4) clean surfaces of metal plate.


根据上述的真题分析,运用我们讲解过的方法便顺利完成了这道题目。可能有的学生无法完成拿到15分的分值,那么应用上述解题思路,失分点就控制在Methods of data collection以及最后的Additional detail这两块中。由于几个点没有踩到给分点而导致错误,那么也能保证在10分以上的成绩。对于我们Paper5拿20以上的目标也有了良好的保障。