During Science classes, students are supposed to carry out a wide variety of experiments. These practical sessions are meant to assist learners to understand the theoretical explanations. Hence, understanding the Means of Recording Experiment Results is deemed very important for both students and teachers.
It is advisable to take as many values as possible and make a table of the values
– All the readings must be taken to the same number of significant figuresSignificant figures: Any digit of a number that is known wit... or decimal places.
Example 1: in an experiment aimed at determining the resistanceResistance is any mechanical force that tends to retard or o... More of a metal, the following readings were obtained: The voltmeter read 5.2V and the ammeter 2.3A. The resistanceResistance is any mechanical force that tends to retard or o... More was calculated as follows:
R=(5.2)/(2.3)=2.252
This answer has the wrong number of significant figuresSignificant figures: Any digit of a number that is known wit.... The correct value should be 2.3(i.e. to two significant figuresSignificant figures: Any digit of a number that is known wit...) since the number of significant figuresSignificant figures: Any digit of a number that is known wit... of the least precise value (2.3 or 5.2) is two
– The number of significant figuresSignificant figures: Any digit of a number that is known wit... in all calculations made from recorded results must be the same as in the results (example above)
Example 2:
|
X(m) |
I(A) |
Y = I(A) |
|
0.000 0.300 0.500 0.700 0.800 0.900 |
0.9 0.48 0.36 0.28 0.26 0.24 |
1.11 2.08 2.78 3.57 3.85 4.17 |
Table 1.1: Data presentation in a table
The results recorded can be used to draw graphGraph is a visual representation of the relations between ce... More. The graphs could be curves or straight lines.
– The points should be correctly plotted on the graphGraph is a visual representation of the relations between ce... More paper
– If the scale is not provided, then an appropriate scale must be chosen
– GraphGraph is a visual representation of the relations between ce... More could be interpreted in different ways.
– If the graphGraph is a visual representation of the relations between ce... More is a straight line, then we can find the gradientGradient or slope is a graded change in the magnitude of som... More.
Table of Contents
THE SCALE
Check the size of the graphGraph is a visual representation of the relations between ce... More paper and try to choose simple scales that will give a graphGraph is a visual representation of the relations between ce... More which will cover more than half page. For example: choose one large square on the graphGraph is a visual representation of the relations between ce... More paper to represent 10g or 20g.
– Avoid choosing numbers such as 3g, 7g, or 9g as it becomes very difficult to plot fraction for these values
– Avoid choosing a scale that represents an even number of units by an odd number of squares. For example: don’t try to represent 10g by 3 squares on the graphGraph is a visual representation of the relations between ce... More paper
– Determine what each small division on the scale chosen would stand for.
– When the scale has been chosen, make sure that you show it clearly on the graphGraph is a visual representation of the relations between ce... More and indicate the unit of measure
– Label the two axes of the graphGraph is a visual representation of the relations between ce... More with correct symbols and units. The independent variableIndependent variable is a variable whose values are independ... is on the horizontal x-axis(abscissaAbscissa is The value of a coordinate on the horizontal axis...) and the dependent variableDependent variable is a variable in a logical or mathematica... is on the vertical y-axis(ordinateOrdinate is the value of a coordinate on the vertical axis. More)
PLOTTING THE POINTS
– Mark the position of the points with a cross or dot neatly using a sharp pencil
– The plotted points must be joined with a single straight line or a continuous curve. The graphGraph is a visual representation of the relations between ce... More should cover as much of the area of the graphGraph is a visual representation of the relations between ce... More paper as possible. This requires a sensible choice of scale for each axis. It is unlikely that points plotted from real experimental results will all lie on a straight line or smooth curve due to errors. Hence try to produce a straight line or smooth curve which passes through as many of the plotted points as possible or which leaves an equal distribution of points on either side. Refer the graphGraph is a visual representation of the relations between ce... More shown in figure (a) above which shows a best fitting lineBest fitting line (Line of Best Fit) is a straight line dr... More.
Every graphGraph is a visual representation of the relations between ce... More should have the following:
- a title (e.g., LoadLoad or the Resistance force (in physics), is the force that... against extensionExtension is an expansion in length of an elastic spring as ... More)
- both axes labelled with units
- scales being used on each axis
- Points plotted with crosses or with dot and circle.
Deductions from graphs
The straight line graphGraph is a visual representation of the relations between ce... More
If you are required to determine the gradientGradient or slope is a graded change in the magnitude of som... More of a straight line graphGraph is a visual representation of the relations between ce... More, there are two methods that can be used:
a. Choose two labelled points on the graphGraph is a visual representation of the relations between ce... More and the interval between the two points should cover more than half the line.
 |
| GradientGradient or slope is a graded change in the magnitude of som... More of a straight line Method (a) |
b.
|
|
The second method involves the use of a right-angled triangle; once again the points selected on the line must cover at least half its length. The lengths of two other sides of the triangle are determined using the scales on the graphGraph is a visual representation of the relations between ce... More. These values are recorded and the gradientGradient or slope is a graded change in the magnitude of som... More of the line can be calculated using the formula: Gradient=(y_2-y_1)/(x_2-x_1 )=Y/X
 |
| GradientGradient or slope is a graded change in the magnitude of som... More of a straight line Method (b) |
If you want to find a corresponding point given one point on either axes, then read off the point by drawing perpendicular lines to both axes from the given point. Using the graphGraph is a visual representation of the relations between ce... More to predict the readingA Reading on a measuring instrument or tool in physical scie... More of measurements that lie between those actually made is known as ‘interpolationInterpolation is a technique in data presentation which cons...’.
You may be asked to get information from a graphGraph is a visual representation of the relations between ce... More which may not lie within the range of the collected data. Often it is necessary to extend the graphGraph is a visual representation of the relations between ce... More (following the obvious trend) to include the range of the data required. This is called “extrapolationExtrapolation refers to the extension of a graph following t...” and it is illustrated below.
This method is used when obtaining zero on Kelvin scale
1.3.3. THE LABORATORY RECORD OF AN EXPERIMENT:
Your laboratory record of an experiment may be split into the follow sections:
1. Headings: Start each experiment on a new page and write the name of the experiment, its number and the date.
2. Aim:as given at the start of each experiment.
3. Apparatus: write the name of the apparatus used.
4. Theory:you must give only brief and relevant notes
5. Procedure:give a brief description of how the data is obtained, and the order in which it was done
6. Measurements/Data:enter the measurements in a ruled table as far as possible, listing them below each other in a column. Give the units in which each is measured. List all the measurements taken; do not subtract two measurements and only record the difference.
7. Data analysis: convert measured values to SI units and substitute them in the formula.
8. GraphGraph is a visual representation of the relations between ce... More: if a graphGraph is a visual representation of the relations between ce... More is to be plotted, follow the guidelines given in 1.4.1 and 1.4.2 above.
9. Result/Conclusion:this should summarise all that you discovered in the course of the experiment. The final result should be given in a sensible order of accuracyAccuracy is The number of significant figures given in a num... More and should state the units concerned. For example, “the resistivity of the metal all measured to be ”.
10. Discussion:you can suggest here how any improvement can be made to the procedure you followed. Or describe any difficulty you encountered.
N.B. use a capital letter and do not underline or simply use lower cases and underline. E.g. AIM or Aim.
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