Table 2.3: Instruments/Apparatus for measuring length and time

Apparatus	Picture / 3D	Uses
Meter Rule		Measure length up to 100cm.
Tape measure		Measure length or distance of 1m and above.
Vernier caliper		Measure length, depth, internal and external diameter of cylindrical objects more accurately.
Micrometer screw gauge		Measure the diameter of a wire, hair, and very small objects more accurately.
Stopwatch		Measure time

Table 2.4: Instruments/Apparatus for measuring mass and weight

Apparatus	Picture / 3D	Uses
Spring balance		Measure force/weight in Newtons
Triple beam balance		Measure mass of substance
Digital balance		Measure mass of a substance more accurately
Triple lever arm balance		Measure mass of a substance

Table 2.5: Instruments/Apparatus for measuring volume of liquids

Apparatus	Picture / 3D	Uses
Beaker		Measure volume and heating liquids
Measuring cylinder		Measure volume of liquids
Burette		Dispense and measure volume of liquid more accurately
Pipette		Transfer specific but small volumesof liquids

Table 2.6: Instruments/Apparatus for heating purposes in the laboratory

Apparatus	Picture / 3D	Uses
Bunsen burner		Source of heat
Wire gauze		Support beaker or flasks during heating
Tripod stand		Provide stability and support for glassware such as beaker and flask.
Calorimeter		Measure amount of heat of a liquid
Test tube		Hold and heat chemicals and liquids
Kerosene stove		Source of heat.
Gas container		Hold a gas which is used as the source of heat in the laboratory
Test tube holder		Hold a test tube during heating

Table 2.7: Instruments/Apparatus for electrical measument

Apparatus	Picture / 3D	Uses
Ammeter		MeMeasure electric current
Voltmeter		Measure voltage
Galvanometer		Detect and indicate the direction of an electric current
Electric cell/ battery		Source of elecromotive force(emf)
Rheostat		Vary resistance in electric circuit
Battery holder		Hold battery
Bulb		Source of light
Plug key		Turn ON and OFF electricity in a circuit
Connecting wires		Connect electrical devices in a circuit
Metre bridge		Determine unknown resistance of a resistor or a conductor.
Resistance box		Estimat and compare resistances.

Table 2.8: Instruments/Apparatus for light experiment

Apparatus	Picture / 3D	Uses
Plane mirrors		Looking glasses
Lenses		Magnify and diminish images of objects.
Curved mirror		Concave for shaving; in torches. Convex for vehicle side mirrors
Drawing boards		Draw the path of rays of light
Optical pins		Used as object in light experiments
Triangular glass prism		Show the minimum angle of deviation and separate white light into its constituent colours(recall rainbow)
Rectangular glass block		Used to demonstrate the concept of refaction of light rays

Task 2.4
Visit the following school premises;
and then, answer questions (i) - (iii)
(a) Physics laboratory.
(b) Chemistry laboratory.
(c) Biology laboratory.
(i) List the items you see in each room and their uses.
(ii) List the items that are commonly found in all laboratories.
(iii) Discuss these items in groups.

Scientific method is an experimental procedure used in constructing and testing a scientific hypothesis or law. A scientific method consists of the collection of data through observation and experimentation, data analysis, drawing conclusion, and writing scientific report. The concept of scientific investigation
The scientific method is the basic skill needed in the world of science. Always humans are curious on why and how things happen in the world around. The scientific method provides scientists with a well- structured scientific platform to help find the answers to their questions. Commonly, a scientific method is a set of techniques used by scientists to investigate a problem or answer questions. Basic steps of scientific investigation
Scientists including physicists are always looking for scientific evidence. A systematic search for evidence is recommended during Student's Book Form One Introduction to laboratory practice and after experiments. The following are steps followed when carrying out a scientific investigation.

1. Problem identification
This is the first step in the scientific method. It is when one makes a puzzling observation. An example of such an observation would be 'What is the relationship between the length of the string to which the pendulum bob is attached to the time taken by the pendulum to complete a given number of oscillations'?

2. Formulating a testable hypothesis
A hypothesis is a scientific assumption or prediction of the outcome. It is a suggestion of the answer to the question asked. For example, 'Length of the string to which the pendulum bob is attached affects the time taken by a pendulum to complete a given number of oscillations'.
FACT: In science we never prove an hypothesis through a single experiment because there is a chance that you made an error somewhere along the way. What you can say is that, your results support or do not support the original hypothesis.

3. Performing an experiment
An experiment is a test under controlled conditions. In this case, the aim of the experiment is to determine whether the formulated hypothesis is true or false. In an experiment, variables are used to test the hypothesis. Variables are those conditions in an experiment that can change or be changed, so as to obtain a set of values. There are three different types of variables, namely; dependent, independent, and controlled variables.

(a) Dependent variable: A variable which changes if the experimental condition changes. For example, the dependent variable is the time it takes for the pendulum bob to complete a given number of oscillations.

(b) Independent variable: A variable which does not change even when the experimental condition is changed. For example, length of the pendulum bob is independent variable.

(c) Controlled variable: This is a variable that is kept constant during an For example, the number of oscillations is a controlled variable.

4. Data collection and analysis
Data collection involves recording what has been observed during the experiments. The observed results are tabulated (recorded in a table form) and ready for analysis. This involves ploting graphs, calculating mean, standard deviation, and errors. The results of the experiment can be recorded as shown in Table 2.9.

Table 2.9: Length of the string to which the pendulum bob is attached and time taken to complete number (n) of oscillations.



5. Data presentation and interpretation
Data presentation involves the use of charts, graphs and mathematical formulae.

Drawing graphs in science
For all graphs plotted from experimental data, it is important to remember that you should not connect the dots. Data will not always follow a line or curve perfectly. By obtaining several experimental data points any discrepancies in each data point can be removed. The data points plotted should be fitted by drawing a best line that passes through most of the points.
The graphs you plot must have the following features:

(a) An appropriate scale is used for each axis so that the plotted points must occupy enough axis/space (work out the range of the data and the highest and lowest points).

(b) The scale must remain the same along the entire axis and should use easy intervals such as 10 s, 20 s, 50 s. Use graph paper for accuracy.

(c) Each axis must be labelled with what is shown on the axis and must include the appropriate units in brackets, e.g. Temperature (°C), time (s), height (cm).

(d) The independent variable is generally plotted along the x-axis, while the dependent variable is generally plotted along the y-axis.

(e) Each point has an x and y co-ordinate and should be plotted with a symbol which can be easily seen, e.g., a cross or circle.

(f) A best fit line should be drawn to the graph.

(g) Do not start the graph at the origin unless there is a data point for (0,0), or if the best fit line runs through the origin.

(h) The graph must have a clear, descriptive title which outlines the relationship between the dependent and independent variable.

(i) If there is more than one set of data drawn on a graph, a different symbol (and/or colour) must be used for each set and a key or legend must be included to define the symbols.

(j)Use line graphs when the relationship between the dependent and independent variables is continuous.

(k) For a line graph, you can draw a line of best fit with a ruler. Make sure the number of points are distributed fairly and evenly on each side of the line.

Introduction to laboratory practice Example of a graph of period, 72 (s²) against length /(m) is shown in Figure 2.26.



(l)In an exponential graph a best fit line should be drawn by using freehand.

After recording and analyzing the data, you may look for possible trends or patterns and explain why they occur that way. For instance, physicist may notice that as the length of the string to which the bob is attached increases, the time to complete a given number of oscillation also increases. This pattern forms the basis on which evidence can be obtained.

6. Drawing a conclusion
A conclusion is a summary of the result of the experiment. It includes a statement that either proves or disapproves the hypothesis. For instence, 'Length of the string to which the pendulum bob is attached affects the time taken by a pendulum to complete a given number of oscillations' proves our hypothesis. The experiment may be repeated to make sure the results obtained are reliable.

7. Reporting results
Scientists communicate their results to others in a final scientific report. It is very important to communicate scientific findings to the public in the form of scientific publications, at scientific conferences, in articles, TV or radio programmes. The experimental results are presented in a specific format, so that others can read your work, understand it, and repeat the experiment. The structure of a good scientific report includes:

(a) Aim - a brief sentence describing the purpose of the experiment;

(b) Apparatus - a list of the apparatus or equipment;

(c) Method - a list of the steps followed to carry out the experiment;

(d) Results - tables, graphs and observations about the experiment;

(e) Discussion - what your results mean; and

(f) Conclusion - a brief sentence concluding whether or not the aim was achieved.

Note: If your results do not support the hypothesis:

(a) do not leave out the experimental results;

(b) suggest possible reasons for the difference between your hypothesis and the experimental results; and

(c) suggest ideas for further investigations so as to find answer to the problem.

Scientific method flow chart



Task 2.5
In a group of 3 or 4 students study the flow chat provided in Figure 2.27, then discuss the following questions:

1. Once you formulate a research problem explain, why is it important to conduct background research before doing anything else?

2. What is the difference between a dependent, independent, and controlled variable and why is it important to identify them?

3. What is the difference between identifying a problem, a hypothesis, and a scientific theory?

4. Why is it important to repeat your experiment if the data fits the hypothesis? Activity 2.1
In this activity you are required to design your own experiment. Use the information provided below and the scientic method flow chart outlined. previously to design your scientific experiment. The experiment should be handed in 1-2 page report. Below are basic steps to follow when designing your own experiment.

1. Ask a question which you want to find an answer.

2. Perform background research on your topic of choice.

3. Write down your hypothesis.

4. Identify important variables of your investigation; those that are relevant and you can measure or observe.

5. Decide on the independent and dependent variables in your experiment and variables that must be kept constant.

6. Design the experiment that you will use to test your hypothesis:

(a) State the aim of the experiment.

(b) List all the apparatus (equipment) that will be used in your experiment.

(c) Write the method that will be used to test your hypothesis in the correct sequence, with each step of the experiment numbered.

(d) Indicate how the results should be presented and what data are required.

Do Activity 2.1

Activity 2.2
Aim: To apply the scientific investigation method in order to test the accuracy of stopwatches.

Materials: Sellotape, table, pendulum bob, string, retort stand, analogue, and digital stopwatches.

Procedure

1. Arrange a simple pendulum system as shown in Figure 2.28.



2. Pull the bob slightly to one side then release it so that it swings back and forth.

3. Using analogue stopwatch, measure the time the pendulum takes to swing back and forth.

4. Record your observation for one complete oscillation.

5. Repeat steps 3 and 4 using the digital stopwatch instead of the analogue one.

Do Activity 2.2

Questions
With reference to the pendulum bob, use the scientific method outlined previously to investigate whether the digital stopwatch is more accurate than the analogue stopwatch in measuring the time taken to complete one oscillation. Briefly address the following:

(a) Develop a hypothesis;

(b) Design and conduct an experiment to test the hypothesis;

(c) Draw a conclusion from the experiment;

(d) After comparing the measurements, which stopwatch do you think is more accurate than the other? And

(e) Write a report explaining your experiment and conclusions.

The measurement from a digital stopwatch is more accurate than the one from an analogue stopwatch. The digital stopwatch therefore, gives a more precise measurement of time than the analogue one.

Task 2.6

1. Discuss with your teacher the steps for carrying out experiments using the scientific method.

2. In groups of five students, discuss the application of the scientific investigation method for a simple pendulum.

3. Briefly explain the importance of forming hypothesis before doing an experiment.

Chapter summary
1. A laboratory is a special room that has been designed and equipped for carrying out scientific experiments for the purpose of study or research.

2. Laboratory rules and safety measures should be observed while carrying out experiments in the laboratory. This is to ensure your safety and that of the other laboratory users.

3. First Aid is the immediate assistance injured or care given to a sick or person before getting a professional medical help.

4. Items for rendering First Aid are contained in the First Aid kit.

5. First Aid helps to save life; it prevents the victim's condition from becoming worse, promotes recovery by bringing hope and encouragement, helps to reduce pain and suffering and also prevents infection.

6. First Aid can be given to victims of: electric shock, cuts or wounds and fainting.

7. Warning signs show whether a substance is harmful, toxic, irritant, flammable, oxidant, corrosive, explosive or can easily break.

8. Warning signs must be read and understood so as to avoid accidents in the laboratory.

9. Apparatus used in a Physics laboratory are tools and instruments required for effective learning and teaching of Physics.

10. The scientific method is a procedure used by scientists to investigate a problem or answer questions.

11. The scientific investigation method is divided into several steps, namely: problem identification, asking questions, formulating a testable hypothesis, performing an experiment, data collection and analysis, data presentation, data interpretation, and drawing a conclusion.

Section A

Choose the most correct answer

1. When a large body of experimental evidence supports or does not support a hypothesis, what may the hypothesis eventually be considered?
(a) Observation.
(b) Insight.
(c) Conclusion.
(d) Law.

2. Which of the following best describes a variable?
(a) A trend that shows an exponential relationship.
(b) Something whose value can change over multiple measurements.
(c) A measure of how much a plot line changes along the y-axis.
(d) Something that remains constant over multiple measurements.

3. Write TRUE for correct and FALSE for incorrect statements for each of the following:
(a) You should move a victim of electric shock using a metallic object.
(b) First aid helps to save life.
(c) Eating in the laboratory is prohibited.

4. Fill in the blanks.
(a)__is an immediate assistance given to a__ before getting professional medical care.
(b) Take the victim to__ if he or she does not regain consciousness. Section B
5. Briefly answer the following questions.
(a) What is a physics laboratory?
(b) List ten laboratory rules.
(c) Name five items found in a First Aid kit and state their uses.
(d) Why it is necessary to wear gloves when giving First Aid to a bleeding person?

6. Outline four features of a good laboratory.

7. What should you do in the laboratory in the event of the following situations?
(a) You need to carry out an experiment but there is nobody in the laboratory.
(b) You have just finished your physics experiments for a day.
(c) Your partner is cut by glass during the experiment.
(d) You want to burn waste papers.
(e) Your partner breaks a beaker.
(f) You have water and you want to drink it.
(g) One of your partners suggests that you take the apparatus out of the laboratory in order to finish the experiment at home.
(h) Your partner wants to insert a bare wire in an electric plug.

8. State six classes of fire and their most appropri ate fire extinguishers.

9. What are warning signs?

10. What do the following warning signs mean?







11. Draw the following apparatus and state its uses:
(a) Beaker.
(b) Thermometer.
(c) Micrometer screw gauge.
(d) Spring balance.
(e) Measuring cylinder.

12. Why is it important for all apparatus used in electrical experiments to be thoroughly dried? Explain.

13. (a) What is a scientific method?
(b) Use a diagram to name all the steps involved in a scientific investigation. (c) As part of their study, Form 2 students were asked to find out whether girls in their class perform better than boys in physics. If you were one of them:
(i) ask the questions;
(ii) propose the hypothesis;
(iii) carry out an experiment to test your hypothesis; and
(iv) draw a conclusion from your experiment.

14. A student investigated the strength of different fridge magnets by putting.

small sheets of paper between each magnet and the fridge door. The student measured the maximum number of sheets of paper that each magnet was able to hold in place. Why was it important that each small sheet of paper had the same thickness?
Before starting the investigation, the student wrote the following hypothesis, 'The bigger the area of a fridge magnet the stronger the magnet will be'. The student's results are given in Table 2.10.



Give one reason why the results from the investigation do not support the student's hypothesis.