AS物理實驗Paper3該如何答題?

物理實驗怎么考?這是復習到最后所有學生都被困擾到的問題，實驗操作是獲得準確數據的基礎，也是讓整個實驗不出錯誤的保障。

而將操作規范放一邊不談，我們今天就談談針對實驗卷paper3的第一個題型，該如何作答，如何表述自己的數據才能讓自己盡量多的拿到最后的分數。

P3 的第一題具有固定的實驗思路，當然也有統一標準的答題模式。

按照題目的思路，首先應該是用某一種測量儀器測量，記錄第一組數據，請你注意，在你寫下第一個數據的同時，也向閱卷人宣告了自己所用儀器的誤差或精確度，在你之后的所有對相同物理量的測量時，精確度必須保持一致!

例如，你在用米尺測量長度，那么可以寫為325px，因為我們的米尺誤差就是2.5px,可如果你寫成325px、325px，那可就犯了個大錯誤!

寫完第一組數據后，接下來就是改變自變量，分別得到六組因變量數據，然后做表格，畫圖(90%+是直線)，求斜率，求截距，給定方程求常量，大致也就這幾個步驟了!

接下來，我們一起來解析CIE官方給出的學習指導：

Paper 3 Tips: Practical Test

▶Do not panic if the context of the practical experiment appears unfamiliar. Where appropriate the question paper will tell you exactly what to do and how to do it.?(按照試卷的要求進行傻瓜操作就可以了，不用多想!)

▶If you find yourself in real difficulty setting up your practical equipment you may ask your supervisor for help, you will only lose one or more marks for this.(請老師幫忙也要付出代價的哦!但如果你真的不會連或者找不到電路中的錯誤又能纏著老師幫你到底的話，幾分也是值得的吧?)

▶There are a number of things that you can do to save time: Draw a single table for your results in advance of taking any readings and enter your readings in the table as you take them (so that you do not waste time having to copy them up later).(先思考需要記錄的物理量，共有多少個?分別是什么?表格應該有幾行幾列?)

This is also important because you must record all your raw readings before you calculate and record any average readings.(真很簡單吧?不解釋!)

If the number of readings that you need to take is indicated in the question paper do not waste time by exceeding this number. Repeat your readings, but remember that it is only necessary to repeat them once (so that you have two sets of values) - do not waste time repeating them more than once.

▶All the raw readings(記得是測量數據哦，可不是計算得值哦!)?of a particular quantity should be recorded to the same number of decimal places which should in turn be consistent with the uncertainty in the readings.(一句話，同一個物理量測六次，精確度必須相同，不解釋!)

▶The uncertainty in a measurement can sometimes be larger than the smallest interval that can be measured by the measuring equipment. For example, a stopwatch can measure time to a hundredth of a second, but human reaction times will mean that the uncertainty in the reading given by a stopwatch is (typically) 0.1s to 0.4s.?(建議各位把各種測量儀器的使用方法及誤差在考前做一個總結，事半功倍!)

▶Each column heading in your table must contain both a quantity and its unit. For instance if you have measured time “t” in seconds, your column heading would be written as “t/s” (“t in s” or “t(s)” would also be acceptable). The quantity or unit or both may also be written in words rather than symbols.?(這就是傳說中的表頭了，這可是閱卷人評閱表格的第一項，第一印象的重要性就不要我重復了吧。)

▶The number of significant figures used in a derived quantity that you calculate from your raw readings should be equal in number to (or possibly one more than) the number of significant figures in the raw readings.?(這個沒有理由，convention，出軌了后果自負吧!)

For example, if you measure potential difference and current to 2 and 3 sig figs respectively, then the corresponding value of resistance calculated from them should be given to 2 or 3 sig figs, but not 1 or 4. If both were measured to 3 significant figures, then the resistance could be given to 3 (or 4) sig figs.?(從這里也可以看出，同一豎向列里的數據，有可能小數點后的位數會不同，但并不影響結果。)

▶When drawing your graph, do not forget to label each axis with the appropriate quantity and unit,(和表頭一樣重要，您自己掂量，是不是應該在選取分度值之前先把他們給標上呢?)?using the same format for expressing column headings in a table.

Choose a scale such that the plotted points occupy at least half the graph grid in both the x and y directions.(此處有技巧，減減除除約約，完事!)

The x-axis scale should increase positively to the right and the y-axis scale should increase positively upwards. Use a convenient scale such as 1, 2 or 5 units to a 50px square?(建議您就用這個吧，別弄個3,4,6的，搬了石頭砸自己的腳，好疼的!)as you will then be less likely to make a mistake with the position of your plotted points and it will be easier for you to read off points from your graph if you are calculating the gradient or finding an intercept. Similarly, it is good practice to mark values on at least every other 50px square.

▶All your plotted points should be on the grid; points in the white margin area will be ignored. Plot all your observations and ensure that they are accurate to half a small square. A fine cross (or an encircled dot) drawn with a sharp pencil is acceptable, but be careful not to obscure the position of your points by your line of best fit or other working.?(鉛筆削細，描點畫叉，做線細又直，千萬別把點給蓋了!)

▶When drawing your line of best fit, ensure you have an even balance of points about the line along its whole length. If it is a straight line, use a clear plastic rule so that you can see points on both sides of the line as it is being drawn.?(盡量多的過點，不在線上的點均勻分布在直線兩側)

▶Show all your working when calculating a gradient. It is helpful to draw the triangle(做好虛線的直角三角形哦)?used to calculate the gradient on the graph and to clearly label the coordinates of the vertices(標好你所選擇的用來計算斜率的兩個點的坐標)?(accurate to half a small square).

These values can then be used in the gradient calculation. The length of the hypotenuse of the triangle should be greater than half the length of the graph line.?(選點選兩頭，不要選表格中的點，以免引起誤會解釋不清)

▶If you are required to give a value for the y-intercept, it may be possible to directly read it off from your graph(如果直線與y軸有交點，太好了，直接讀取)?from an axis where x=0. If this is not possible you can instead calculate the y-intercept by using the equation of a straight line.?(如果沒有與y軸相交，那就把算斜率的點帶進直線方程去求吧)

In this case you should substitute into this equation a pair of x and y values from your line of best fit along with your calculated value of gradient.