Schoolgen Sister Schools Cluster Day at Greenhithe Primary School.

Weeks of planning came to fruition.  Maggie, Katie and myself had worked hard to get the first “sister schools” day off the ground. The day went very well and the two activities I had designed seemed to work and be enjoyed by almost all the students. According to the evaluation forms they particularly enjoyed the turbine making activity :-)! It even made the North Shore Times with a photo of a girl (aged 10) admiring her freshly minted turbine. The children were from 12 schools in the area and ranged from Years 5 to 8. They were all very well behaved and keen to learn (such a refreshing change!). The format was 5 activities of half an hour interspersed with 3 presentations, morning tea and lunch. the time frame was quite tight for the turbines but was just enough. The kids were able to make a turbine with me and Caroline’s assistance and got 5 minutes teaching on Pelton wheel turbines and how they generate electricity by moving a magnet past a conducting coil.

I was lucky to have the props of my F&P smart-drive still attached to the plastic tub from the washing machine, an Ecoinnovation Pelton wheel micro-hydro generator from work which uses a rewired smart-drive as its generator.

The kids loved seeing the sparks when one of them turned the rotor and the other brushed the wires and were able to easily see the magnets and coils when the rotor was screwed off. They were fascinated that you could power your house with one of these. I left them with the idea of continuing on their enquiry by building a housing for their turbine and attaching a motor/generator via a gear, again seeing the example I had made was empowering for them.

Measuring light with a data logger

 

Aim of the Activity

Students have 20 minutes to investigate visible light intensity (measured in “lux”) using a data logger with a built-in light sensor. Two aspects will be investigated (by separate sub-groups?)-

1. How changing angle of the sensor to the light source affects light intensity (keep distance constant).
2. How changing distance from the light source (lamp) affects light intensity (keep angle fixed perpendicular to sensor).

 Focus- Possible background & discussion questions to this activity.

1. The earth is about 150 million kilometres away from the sun, this distance only changes by a small amount through the year as the earth orbits it. How much stronger or weaker would the sun be on Venus (108 million km from the sun), or Mars (228 million km from the sun)? Something to think about doesn’t have to be answered straight away.
2. In Auckland in summer the highest sun angle is about 77 degrees above the horizon and in winter it is only about 30 degrees. What would be the best angle for a PV panel on a north facing roof?
3. Photovoltaic (solar electric) and solar hot water (solar thermal) panels are mounted on roofs which have different pitch (steep, shallow or flat roofs) and orientation (NSEW) relative to the sun. What do you think is the best angle and orientation for these panels?
4. The light sensor on the data logger is like a tiny photovoltaic panel, it converts light energy into electrical energy and this is then converted into a reading measured in lux, showing how strong or intense the light appears to the human eye. What is the background light intensity in the room? If you shine a light on it how will it change? How many lux is direct sun light?
5. Light bulbs have a power rating in Watts (eg. 100 W) which measures how much electrical energy it uses every second. What type of bulb is hotter, the traditional incandescent or the CFL? Does all of the electrical energy get converted into light we can see? How can CFL bulbs emit about the same amount of visible light as traditional bulbs, but consume much less power?

 Equipment-

• Data logger with lux meter (x2).
• Laptop with data logger software loaded.
• Lamp adjustable angle with 100W incandescent light bulb.
• Small photovoltaic panel with electric motor for context (x2),

• Optional- current sensor to measure the output of the photovoltaic panel.

 For Investigation 1:

• Large protractor and string, to measure angle between light source and plane of light sensor OR (preferred) Make your own angle measuring device from cardboard (hypotenuse 50cm)- 2 angles can be measure with 1 triangle.

 For Investigation 2:

• Tape measure or 1 metre rule.

Method for investigation 1 – Changing the angle of incidence

1. Place the data logger/light sensor lying flat on the table.
2. Use the hypotenuse of the cardboard triangle to position the lamp at the correct distance and angle to the light sensor.

1. Using the display meter on the computer, record the light intensity (measured in lux) in the results table below. Record two values for each distance, one with the light off, and one with the light on.

 

1. To get the effect of the light intensity due to the lamp only, subtract the value with the lamp ON from the value with the lamp OFF and write in the final column of the results table below.

 

Angle (degrees)	Lamp OFF (lux)	Lamp ON (lux)	Difference (lux)
20
30
40
50
60
70
90 (directly above)

 

Method for investigation 2 – Changing the distance

1. Setup the equipment as shown in the photographs below, with the tape measure stretched out to 1m lying on the desk and the data logger sitting upright. Try to ensure that the lamp and light sensor are perpendicular to each other.

 

1. Position the lamp above the start of the tape measure. Move the sensor/data logger to the distance to be measured from the lamp (start at 1.0m).

 

1. Using the display meter on the computer, record the light intensity (measured in lux) in the results table below. Record two values for each distance, one with the light off, and one with the light on.

 

1. To get the effect of the light intensity due to the lamp only, subtract the value with the lamp ON from the value with the lamp OFF and write in the final column of the results table below.

 

Results

1. Record the data in the TABLE:

 

Distance (cm)	Lamp OFF (lux)	Lamp ON (lux)	Difference (lux)
100
80
60
40
20

 

1. Graph the light intensity (due to the lamp) vs. distance. Make sure that distance is on the horizontal axis.
2. Describe in words how changing distance from the light source (lamp) affects light intensity.
3. Year 10 High School students could be shown a series of y vs. x graphs* and recognise which one it resembles most (y = 1/x²).

y vs x, y vs 1/x, y vs x², y vs 1/x²

1. Senior High School physics students might be able to state what physical relationship it obeys (the Inverse square law). The mathematical relationship behind gravitation, light intensity (irradiance), electrostatic force etc. Note that you won’t get an exact inverse square law relationship as the lamp is too close and therefore not strictly a point source.

 

Measuring Light- links to the NZ Curriculum with ideas for extension.

 Suggested Principles

Future Focus

“Encourage the making of connections across the learning areas, values and key competencies … relevant to students’ futures.”

Sustainability-

 Long term impacts on environment/society.

Enterprise-

 Innovation through working effectively with the forces of nature.

Coherence

“… makes links within and across learning areas, … and opens up pathways to further learning.”

• Suggested Values

Innovation, inquiry, and curiosity

Thinking “critically, creatively, and reflectively”. 

Ecological sustainability

• Suggested Key Competencies 

Thinking– make sense of information, experiences and ideas. Intellectual curiosity.

Use Language, symbols & texts – interpret and use words, number, images… and technologies in a range of contexts

Managing self– manage time frames, reflect/respond to ideas encountered.

 Relating to others–     work in pairs/small groups, share ideas, cooperate.

Participating & Contributing– Bigger picture context. Knowledge may lead to action.

• Suggested Learning Areas

Science

Physical World–

Transformation of energy- light to electrical energy.

Sun light is solar energy radiated through space to the planets.

Planet Earth & Beyond–

Sun- the source of renewable energy.

Solar System/Planets–

Use the graphical/mathematical relationship found between distance and light intensity to predict the solar intensity on other planets.

Earth-

Seasons related to axial tilt.

Nature of Science-

Investigate how the scientific discoveries behind light eventually led to useful technologies.

Technology

Technological Practice–

“Students examine the practice of others and undertake their own”.

Technological Knowledge–

“Students develop knowledge particular to technological enterprises and environments and understandings of how and why things work.”

Nature of Technology–

“…learn to critique the impact of technology on societies”

Further possible areas to extend investigation of hydroelectric generation:

Social Sciences

Impacts on remote/poor communities of solar technologies.

Mathematics

Collect/record, graph and interpret data.

Relate mathematics to the physical world.

Level 3 – 4

-SCIENCE-

Nature of Science
Investigating in science 

Students will ask questions, find evidence, explore simple models, and carry out appropriate investigations to develop simple explanations.

Physical World
Physical inquiry and physics concepts

Students will explore, describe and represent patterns and trends for everyday examples of physical phenomena, such as movement, forces, electricity and magnetism, light, sound, waves, and heat.

Astronomical Systems
Students will investigate the components of the solar system, developing an appreciation of the distances between them.

-MATHS-

Number & Algebra 

Patterns & Relationships 

Relate tables, graphs and equations to… simple relationships found in number and spatial patterns.

Geometry & Measurement 

Measurement 

Position & Orientation 

General exposure to some of these concepts using the cardboard triangle to measure distance and angle.

Level 5-6

-SCIENCE-

Nature of Science
Investigating in science

Students will develop and carry out more complex investigations, including using models.

Students will show an increasing awareness of working scientifically, including recognition of multiple variables.

Physical World
Physical inquiry and physics concepts

Students will identify and describe the patterns associated with physical phenomena found in simple everyday situations involving movement, forces, electricity and magnetism, light, sound, waves, and heat.

Using Physics 

Explore a technological application of physics.

Astronomical Systems 

Students will investigate the conditions on the planets … and the factors affecting them. 

-MATHS-

Number & Algebra 

Patterns & Relationships 

Relate tables, graphs and equations to… simple relationships found in number and spatial patterns.

Geometry & Measurement 

Measurement 

“Select and use appropriate units for length … angle (light intensity) with awareness that measurements are approximate.”

Web links:  Eg. Inspirational young female scientist developing new kinds of cheap solar cells that could revolutionise power in remote/poor communities.

http://www.youtube.com/watch?v=W8eNeReo-hw