TECHNIQUE OF ANSWERING SPM

PHYSICS PAPER 3 [4321/3]

ANSWER STRATEGY PHYSICS QUESTIONS PAPER 3Written Practical Questions (1 Hours 30 Minutes)

SECTION ASection A consists of two structured questions.

You need to answer all questions from this section.

This section is allocated a total of 28 MARKS.

Section A (Questions 1)1. The questions in this section are based on experiments that you should have already done in the laboratory.2. The questions in this section normally require you to: - State the variables base on the experiment given. (You are normally required state the manipulated variable, the responding variable and the constant variable based on the aim and the procedure of the experiment) - Record the data and do the tabulations. (Make sure you know how to tabulate the data correctly). - Plot a graph. (Make sure you know how to plot a graph correctly) - State the relationship between two variables from the graph.

3. You are advised to spend 40 minutes on this section.

Section A (Questions 2)1. The questions from this section also involve the interpretation of graphs. 2. You will also need to know how to determine the gradient and the unit of the gradient of a graph. 3. The questions from this section may also involve the calculation of certain quantities. Make sure that you write down all the steps involved in the spaces provided in the questions paper. (Make sure you know how

to use the value of the gradient in the calculation)4. You may need to state the precaution of the experiment.5. You are advised to spend 30 minutes on this section

SECTION B1.Section B consists of two questions. You

need to answer ONE question only from this section.

2. This section is allocated a total of 12 MARKS.

3. You are advised to spend 30 minutes on this section.

4. The questions in this section are normally base on the diagram of a situation in our daily lives together with a brief write-up on the situation.

5. You will have to study the situation carefully and try to find the variables related in the situation.

6. You will also be asked to state one appropriate inference, hypothesis for an investigation and to describe an experimental framework to test hypothesis. In your description, you will have to state clearly the following:(i)Aim of the experiment(ii) Variables involved in the experiment(iiii) List of apparatus and materials(iv)Arrangement of the apparatus(v)The procedure of the experiment which includes

- the methods of controlling the manipulated variable

- the method of measuring the responding variable- the method of repeated experiment(vi) The way you would tabulate the data(vii) The way you would analyse the data

7. Make sure that you describe your experiment according to the format shown above.

Section A[28 marks]

Answer all questions in this sectionA student carries out an experiment to investigate the relationship between the length of wire, l, and its resistance, R.The arrangement of the apparatus is shown in Diagram 1.1. An ammeter, dry cells, a rheostat, a switch and piece of constantan sire are connected in series.A voltmeter is used to measure the potential difference, V, across the constantan wire between P and Q.

A constantan wire of length, l = 20.0 cm is connected between P and Q. When the switch is on, the rheostat is adjusted until the ammeter reading is 0.50 A. The voltmeter reading, V, is as shown in Diagram 1.2 on page 4.The corresponding voltmeter reading across P and Q are shown in Diagram 1.3, 1.4, 1.5 and 1.6 page 4.

(a) For the experiment describe on pages 2 and 3, identify:

The manipulated variable Length of (wire) / l

[1 mark]

(b)The responding variableResistance / R // Potential difference / V // Voltmeter reading // Voltage *Rej: voltmeter

[1 mark]

(c) The constant variableDiameter of wire // Type of wire // Current // Thickness // Cross-sections of wire // Radius // Ammeter reading // SWG // Resistivity // Temperature*Rej: Size, no of battery, emf, dge

[1 mark]

b) Based in Diagram 1.2, 1.3, 1.4, 1.5 and 1.6 on page 4: Record the voltmeter readings, V, in the spaces provided on page 4.

Diagram 1.2 : 0.4 VDiagram 1.3 : 0.9 VDiagram 1.4 : 1.3 VDiagram 1.5 : 1.7 VDiagram 1.6 : 2.2 V

[2 marks](i) Calculate the values of R for each length of wire using the formula R = V/0.5

Diagram 1.2 : 0.8 ΩDiagram 1.3 : 1.8 ΩDiagram 1.4 : 2.6 ΩDiagram 1.5 : 3.4 ΩDiagram 1.6 : 4.4 Ω

[2 marks]

(ii) Tabulate your results for V and R for all values of l, in the space below.

[3 marks]l / cm V / V R / ohm

20.0 0.4 0.8

40.0 0.9 1.8

60.0 1.3 2.6

80.0 1.7 3.4

100.0 2.2 4.4Note:Values of l, V and R shown in the tableState the units of l, V and R correctlyThe values of l, V and R are consistent to one or two decimal place.

(c) On the graph paper on page 6, plot a graph of R against l.

Show R on the vertical-axis and l on the horizontal-axis

State the units of the variable correctly / symbol of units

Both axes are marked with uniform (even) scale

* (1:1, 1: 2, 1:4, 1:5, 1:10)* Rej: Odd scale All five points are plotted correctly * 1 (2 mm x 2 mm)* 5 points – 2m * 3-4 points – 1mBest fitted straight line * point to the line 5 mm @ 2.5 Show the minimum size of graph at least 5

(y) x 4 (x) ( 10 cm x 8 cm) square * Start from the origin until the last point

[7 marks]

(d)Based on your graph in 1(c), state the relationship between R and l.

Resistance of wire (R) is directly proportional to the length of wire (l)/

R α l / l α R / Increasing linearly [1 mark]

2. A student carries out an experiment to investigate the relationship between the mass, m, of a load placed on a spring and the length, l, of the spring. The student also determines the spring constant, k.The result of this experiment is shown in the graph of l against m in Diagram below.

(ii) determine the value of l when m = 0 g.

l = 9.5 – 10 cm- show graphical extrapolation

correctly- state the value within acceptable

range

[2 marks]

(a) Based on the graph in Diagram 2.1(i) what happens to l as m

increases?Increases // longer //

extended // greater length // bigger length //

higher length[1 mark]

(b) The spring constant, k, is given by the formula k = 1/h, where h is the gradient of the graph.

(i) Calculate the gradient, h, of the graph.

Show on the graph how you calculate h.

[3 marks]

h = (22.5 – 10)/60= 0.208 cm g-1

- Draw a sufficiently large triangle ≥ 8 cm x 8 cm- Correct substitution- State the value within acceptable range and correct unit* Reject : answer in fraction

(ii) Determine the value of k. [2 marks]

k = 1/h= 4.81 g cm-1

- Correct substitution- State the value of k within the acceptable range

k

1

k

1

k'

1'

Calculate k’.

k’ = …………………………. [2 marks]

(c) Another identical spring is connected in series to the end of the spring. The spring constant, k’, of the two springs in series is given by the formula 1/k` = 1/k + 1/k

(d) State two precautions that can be taken to improve the accuracy of

the readings in this experiment.Repeat readings and take

averageEye perpendicular to the

scale/reading to avoid parallax error.Ensure the spring does not swing

/ at rest when reading is taken. *Rej: parallax error, parallel

[2 marks]

State the value of k’2.41 g cm-1 / 2.405 g cm-1

Section B[12 marks]

Answer any one questions from this section1. Diagram 3 shows two opaque cups, A and B, containing different amount of water. A similar coin is placed at the bottom of each cup.

When the coin is observed from the same position, the image of the coin in cup A cannot be seen, but the image of the coin in cup B can be seen.

Based on your observation on the depth of the water and the position of the images of the coins:(a) State one suitable inference

Depth of water affects the position of image //

Position of image depends on the depth of water

*Note: Must have cause without effectRV influenced by MVRV affected MVMV affects RV

[1 mark]

(b)State one hypothesis that could be investigated.

The more the depth of water, the more the depth of the image // the higher is the image.*Note: Must have cause and effect

[1 mark]

(c) With the use of apparatus such as a tall beaker, pins and other apparatus, describe an experiment to investigate the hypothesis

stated in 3(b)

In your description, state clearly the following;

(i) The aim of the experiment. To investigate the relationship

between the depth of water and apparent depth // real depth and apparent depth

*Note: Relate MV and RV

(ii) The variables in the experiment.Manipulated variable: Real depthResponding variable: Apparent depth

// Depth of image* Note: Both must correctConstant variable: Density of water //

Refractive index // Type of liquid

(iii)The list of apparatus and materials.

Beaker, Water, Pins, Set of retort stand, Metre rule // Diagram

[1 mark

]

(iv) The arrangement of apparatus.- State a functional arrangement of the apparatus*Note: Functional mean experimental can be done or can get a data.

[1 mark]

(v) The procedures of the experiment which include the method of controlling the manipulated variable and the method of measuring the responding variable.

State the method to control manipulated variableFill beaker with water to a depth of d1 = 10 cm / any number or symbol/letterState the method to measure the responding variableMove the pin outside the beaker to obtain the apparent position of the pin in the beaker.Measure the position of the pin from the surface of the water to the pin.Repeat the experiment at least 4 timesRepeat the previous steps by increasing the depth of water 15 cm, 20 cm, 25 cm and 30 cm.

[3 marks]

(vi) The way to tabulate the data.

(vii) The way to analyse the data.

Show how the data is tabulated.*Note: Must have 2 columns

Depth of water, d / cm

Apparent depth, h / cm

10

15

20

25

30

Depth of water/cm

Apparent depth/cm

- If use symbol, must mention earlier.- Accept conclusion, statement of variable related.- h α d