yr. 11 physics – area of study 3: sustainable energy...

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Name: Yr. 11 Physics – Area Of Study 3: Sustainable Energy Sources – Solar Cells Investigating the Solar Cell – Part A

Aim: To investigate the behaviour of a solar cell in varying light conditions. Equipment: • Solar cell

• Multimeter • Connecting wires, one end with alligator

clips, the other with banana plugs. • 100 W incandescent light globe.

(Or 100W equivalent CFL globe.)

A picture of the solar cell that you'll be using.

A diagram of the solar cell that you'll be using showing

its positive and negative terminals.

Method: 1. Connect the solar cell to a multimeter. Make sure that the positive terminal of the

multimeter is attached to the positive terminal of the solar cell (it has a '+' sign on it) 2. Once you have connected the solar panel to the multimeter, turn the multimeter on and

record the voltage for different amounts and sources of light as outlined below. Record the voltage across the solar cell in each of the following situations and describe your observations. a) Directly underneath one of the light banks in your classroom.

b) Against the window or outside in the sunlight. c) Now place the solar cell back under the light in the classroom. What happens to the

reading on the multimeter when you cover up the bottom third of it with an opaque object? When the bottom two thirds are covered? When it is completely covered?

+

-


(3 marks)

Conclusion: What conclusions can you reach from an analysis of your observations for this part of the experiment?

(2 marks)

Investigating the Solar Cell – Part B

Aim: To investigate the effect that the angle of the incident light has on the voltage output of a solar cell.

Equipment: • As in Part A

• Two 1-metre rulers. One with an LED torch taped 40 cm from one end as shown below.

Figure 1a

Figure 1b



multimeter is attached to the positive terminal of the solar cell (it has a '+' sign on it)

2. Once you have connected the solar panel to the multimeter, turn the multimeter on. Record the voltage reading on the multimeter before you switch the torch on and shining it onto the solar cell. Why is this step important?

(2 marks)

3. Vertically place the ruler with the torch attached to it above the solar panel and turn the torch on as shown in Figures 1a and 1b. At this point the torch is at 90o to the horizontal. Record the voltage reading from the multimeter in the table below.

4. Repeat this process for each of the other angles in the results table. Figure 2 shows you how to set up the torch and rulers for each of the angles.

Figure 2

torch

solar cell

metre ruler

20o

34 cm

metre ruler


Results: Voltage recorded before the torch was switched on:

Angle (!! ) Vertical Ruler Height (cm)

Recorded Voltage (V)

Voltage Due To Torch Light (V)

0o 0

10o 17

20o 34

30o 50

40o 64

50o 77

60o 87

90o 100

(4 marks) Conclusion: What conclusions can you reach from an analysis of your observations for this part of the experiment?

(2 marks)

Discussion: How does your conclusion relate to how the solar panels used to power the 40 km/hr speed signs outside of schools are aligned and set up?

(2 marks)


Investigating the Solar Cell – Part C

Aim: To investigate the effect that the distance from a light source has on the voltage output of a solar cell.

Equipment: • As in Part A • Metre ruler • A 100 W light globe or CFL equivalent

• A retort stand and clamp to hold and support the light globe.

• A shoe box with a solar cell mounted against one of the end walls as shown Figure 3a. The other end needs to be cut out to allow light from the light globe to fall onto the solar cell.

Figure 3a

Figure 3b


multimeter is attached to the positive terminal of the solar cell (it has a '+' sign on it)

2. Once you have connected the solar panel to the multimeter, turn the multimeter on. 3. Place the light globe as close as you can to the solar cell. Before you switch the light

globe on measure the distance between the solar cell and the filament of the light globe. Close the lid of the shoebox and record the reading on the multimeter.

4. Turn the light globe on and record the reading on the multimeter. Record your result. 5. Now increase the distance of the light globe from the solar cell by 10 cm. Record the

voltage reading on the multimeter. 6. Repeat Step 5 until you run out of bench space. You should be able to obtain about ten

results altogether!


Results: Voltage recorded before the light globe was switched on:

Distance from light globe (cm)

Recorded Voltage (V)

Voltage Due To Light Globe (V)

(4 marks) In this part of the experiment what were the independent, dependent and controlled variables?

(4 marks)

Which is the best way to represent the data you found- pie chart, bar chart, histogram or line graph? Explain your choice.

(3 marks)

Draw a graph of the dependent variable against the independent variable. (5 marks)

Carefully draw in a smooth line of best fit for the data points on your graph. (1 mark)


Graphing Scoring Guide

Labelling Scaling Choice of graph type

Interpretation Presentation

Exemplary Axes are labelled appropriately with units and graph title is specific and appropriate

Scaling is consistent, most appropriate and in the correct position

Appropriate graph and an alternative representation when appropriate

Intelligent interpretation that shows a thorough understanding of the information

Graph is attractively presented and elicits interest with appropriate title

Proficient Labels on axes and graph with units included

Scaling is consistent and appropriate

Appropriate graph type for the purpose

A logical interpretation of the information

Straight, fine lines with clear legible labels

Progressing Label on graph or axes but not both, or labels inappropriate

Scale is consistent, but not necessarily appropriate

Some recognition of the type of graph required

Graph has some interpretation, but not all is accurate

Parts of the presentation in need of improvement

Not meeting the standard

No labels on axes or the graph, or labelling in incorrect spot

Scales inconsistent and or inappropriate

Not the appropriate graph

No interpretation of the graph

Presentation detracts from the interpretation of the graph

Conclusion: What conclusions can you reach from an analysis of your observations and graph for this part of the experiment?

(2 marks)

Evaluation: In what ways could this part of the experiment be improved upon? Provide an explanation for your suggestions.

(2 marks)


Questions for further discussion: Question 1 What energy transformation(s) takes place in a solar cell?

(1 mark)

Question 2 What energy transformation(s) take place in the torch?

(2 marks)

Question 3 What energy transformation(s) take place in the light globe?

(2 marks)

Question 4 Solar cells have an efficiency of between 18-21%. If a solar cell was 17% efficient and it generated an output of 32kJ, what was the total light input?

(2 marks)


Using A Multimeter For this experiment you will be using one of the two types of multimeters shown below. A multimeter is an electronic device that can be used to measure both AC and DC voltages and currents and resistance. You will be measuring the DC voltage output of a solar cell. This DC voltage is a measure of how much electrical energy is made available by the solar cell to be transformed into other forms of energy in an electric circuit.

To do this you will need to plug a banana plug into the positive (red) terminal and a banana plug the negative (black) or common terminal.

On the face of this multimeter turn the dial so that it points to the following symbol for DC voltages.

This will give you a direct reading of the electrical energy supplied by the solar cell. If the display shows mV before the numbers in the display then it is measuring the voltage in mV. Examples 1000 mV is equal to 1.00 V

25 mV = 0.025 V

On the face of this multimeter turn the dial so that it points to the following symbol for DC voltages, and to the position for 2000mV.

This will give you a direct reading of the electrical energy supplied by the solar cell. Examples 2000 mV is equal to 2.00 V

25 mV = 0.025 V

VV


IGGS – Risk Assessments: Yr. 11 Physics – Solar Cells.

Experiment/Demo/Activity Title: Solar Cells

Location: Science Laboratory Persons exposed to risk: teacher / students

Non-chemical Hazard Perceived Risk/Injury Control Measures

• 240 V AC electricity. • The 100 W light globes

generate a lot of heat when used. At least 5 minutes should be left for the globe to cool down once it has been switched off.

!√ electrocution !√ burns !• impact injury !• laceration !• skeleto/muscular injury !• hearing loss !• infection

!• safety glasses !• heat proof gloves !• ear muffs !• tongs !• dry hands !√ check electrical

leads for any safety issues.

√ exercise care with hot globes.

Waste Management: • Sewerage • Normal rubbish • Collect for special disposal: Risk Assessment Matrix:

Probability Assess the Risk Rating for the worst of the perceived risks above: 1) Assess the

Consequence 2) Assess the Probability 3) Line the two up to

show the Risk Rating.

Overall Risk Rating: Low

Very Likely

Likely Unlikely Highly Unlikely

Con

sequ

ence

s

Fatality

High High High Medium

Ris

k R

atin

g

Major Injury

High High Medium Medium

Harmful

High Medium Medium Low

Negligible

Medium Medium Low Low

Assessment by: Signature: Date:

yr. 11 physics – area of study 3: sustainable energy...

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