Introduction
Measure light levels
Introduction
Light in a greenhouse
Introduction
Standards
Materials
Safety
Procedure
Prediction
Collect Data
Analysis
Further Investigations
Light in a greenhouse - Probe kit
Introduction
Standards
Materials
Safety
Procedure
Prediction
Collect Data
Analysis
Further Investigations
Greenhouse effect in a greenhouse
Introduction
Standards
Materials
Safety
Procedure
Prediction
Collect Data
Analysis
Conclusion
Further Investigations
Greenhouse effect in a greenhouse - Probe kit
Introduction
Standards
Materials
Safety
Procedure
Prediction
Collect Data
Analysis
Conclusion
Further Investigations
Heat and light from electricity
Introduction
Materials
Procedure
Prediction
Collect Data
Analysis
Conclusion
Further Investigations
Heat and light from electricity - Probe kit
Introduction
Materials
Procedure
Prediction
Collect Data
Analysis
Conclusion
Further Investigations
Calibrate the phototransistor.
How bright is it?
This activity has three different data collectors for light, each at a different scale, for different levels of brightness.
In this activity you will build a model greenhouse and explore light levels over the course of a day.
How does a greenhouse work?
Plants obviously grow outside, but often a greenhouse, which is a house for growing plants, is used to provide better conditions for plant growth than the outdoors. What conditions do you think typical plants like? Discuss this with your group members and record your thoughts and ideas below.
How do you think the conditions inside a greenhouse differ from the conditions outside? Think about different times of day and different seasons. Be prepared to discuss your thoughts with the class.
What are some of the physical features of a greenhouse, and how do these features create a good house for plants?
How do greenhouses affect the light levels for plants?
This unit addresses NSES standards for inquiry and physical science at grades 5-8 and NCTM standards on Algebra and Data Analysis at grades 6-8.
- cardboard box, shoebox or plastic container with a clear top and solid bottom
- plastic wrap or clear plastic
- light sensor
- tape, scissors
- light source such as a swivel desk lamp
- Do not touch the bulb of the desk lamp. Severe burns may result.
- Do not look directly at a light bulb. It can hurt your eyes.
- Obtain a box or container to use as your greenhouse. Your “greenhouse” box should look like one of the containers below, with a clear top and a solid bottom. Your teacher will provide a moveable light to represent the sun.
- In this trial, you will investigate light levels in your model greenhouse, with the lamp modeling the sun at five different times of day. The most accurate way to do this is to measure reflected light. To do this, place a white sheet of paper in the bottom of your greenhouse. The sheet of paper should be the same size as the bottom of your model greenhouse, as shown below.
- You will model the times of day by shining a lamp (a model of the sun) on your greenhouse at different angles. Shown below are drawings of the sun’s path over a greenhouse and how you can imitate it with a lamp.
Before taking your data, what do you think the relative light levels will be for these times of day? On the Prediction Graph, indicate how you think light levels will vary over the course of the day. Be prepared to defend your graph.
- Position the lamp as shown below. This will represent dawn. Carefully measure the distance between the lamp and the top of your greenhouse to be 40 cm. Turn the lamp on.
- Start the light sensor. Refer to Technical Hints to connect the light sensor.Point the light sensor at the white paper (the bottom of your greenhouse) to measure the brightness of the reflected light. Note the value on the graph.
- Continue running the graph as you move the light through the positions shown in the picture below. Note the value for each of the different “times of day” and record your measurements below. Be careful to set the lamp at the same distance from your greenhouse for each measurement (40 cm), and to point the light sensor at the white paper, not the lamp.
- Repeat your experiment with plastic wrap over the greenhouse. Does the clear cover change the light level?
- Some greenhouses use shades of various types, because many plants like partial shade. Below is a picture of a shade made of fabric, which can lie on top of a greenhouse.
Put your model greenhouse in real sunlight, which is much brighter than a lamp. Try some shading materials that cut down but do not block the sunlight completely. Record what you tried and what the resulting light level was.
- How does light level change throughout the day in a greenhouse? Discuss how your results compare with your prediction.
- What effect does the clear cover have on light levels?
- How does the light level with shading compare to the light level from a lamp? From full sun?
- Change the light level by moving the light up and down or by setting your greenhouse in full sunlight. Using both the light sensor and the temperature sensor, explore how the light level affects the temperature.
In this activity you will build a model greenhouse and explore light levels over the course of a day.
How does a greenhouse work?
Plants obviously grow outside, but often a greenhouse, which is a house for growing plants, is used to provide better conditions for plant growth than the outdoors. What conditions do you think typical plants like? Discuss this with your group members and record your thoughts and ideas below.
How do you think the conditions inside a greenhouse differ from the conditions outside? Think about different times of day and different seasons. Be prepared to discuss your thoughts with the class.
What are some of the physical features of a greenhouse, and how do these features create a good house for plants?
How do greenhouses affect the light levels for plants?
This unit addresses NSES standards for inquiry and physical science at grades 5-8 and NCTM standards on Algebra and Data Analysis at grades 6-8.
- cardboard box, shoebox or plastic container with a clear top and solid bottom
- plastic wrap or clear plastic
- light sensor. To build the sensor, see:
- tape, scissors
- light source such as a swivel desk lamp
- Do not touch the bulb of the desk lamp. Severe burns may result.
- Do not look directly at a light bulb. It can hurt your eyes.
- Obtain a box or container to use as your greenhouse. Your “greenhouse” box should look like one of the containers below, with a clear top and a solid bottom. Your teacher will provide a moveable light to represent the sun.
- In this trial, you will investigate light levels in your model greenhouse, with the lamp modeling the sun at five different times of day. The most accurate way to do this is to measure reflected light. To do this, place a white sheet of paper in the bottom of your greenhouse. The sheet of paper should be the same size as the bottom of your model greenhouse, as shown below.
- You will model the times of day by shining a lamp (a model of the sun) on your greenhouse at different angles. Shown below are drawings of the sun’s path over a greenhouse and how you can imitate it with a lamp.
Before taking your data, what do you think the relative light levels will be for these times of day? On the Prediction Graph, indicate how you think light levels will vary over the course of the day. Be prepared to defend your graph.
- Position the lamp as shown below. This will represent dawn. Carefully measure the distance between the lamp and the top of your greenhouse to be 40 cm. Turn the lamp on.
- Start the light sensor. Refer to Technical Hints to connect the light sensor.Point the light sensor at the white paper (the bottom of your greenhouse) to measure the brightness of the reflected light. Note the value on the graph.
- Continue running the graph as you move the light through the positions shown in the picture below. Note the value for each of the different “times of day” and record your measurements below. Be careful to set the lamp at the same distance from your greenhouse for each measurement (40 cm), and to point the light sensor at the white paper, not the lamp.
- Repeat your experiment with plastic wrap over the greenhouse. Does the clear cover change the light level?
- Some greenhouses use shades of various types, because many plants like partial shade. Below is a picture of a shade made of fabric, which can lie on top of a greenhouse.
Put your model greenhouse in real sunlight, which is much brighter than a lamp. Try some shading materials that cut down but do not block the sunlight completely. Record what you tried and what the resulting light level was.
- How does light level change throughout the day in a greenhouse? Discuss how your results compare with your prediction.
- What effect does the clear cover have on light levels?
- How does the light level with shading compare to the light level from a lamp? From full sun?
- Change the light level by moving the light up and down or by setting your greenhouse in full sunlight. Using both the light sensor and the temperature sensor, explore how the light level affects the temperature.
By using a temperature sensor, we can relate changes in sunlight to the temperature of the air being trapped in a container.
How is the atmosphere like a greenhouse?
The greenhouse effect is the name scientists use to describe how heat can build up in the earth’s atmosphere.
A majority of the energy from the sun arrives at the earth as visible radiation. This energy passes through our atmosphere and warms the surface of the earth. The warmed surface re-emits radiation but this radiation is not visible as it is in the infrared. Some of this infrared radiation is absorbed by our atmosphere. Our atmosphere absorbs more of the infrared radiation when water vapor, carbon dioxide, and methane are present. The more readily the infrared is absorbed, the greater the net energy gain from sunlight.
The effect of this process was examined using a model in the Greenhouse gases activity. In this activity you will measure the phenomenon in a real greenhouse setting. A glass enclosure — a real greenhouse — works in the same way as the atmosphere to capture heat from sunlight.
This activity addresses NSES standards for earth and space science and inquiry at grades 5-8
(http://books.nap.edu/readingroom/books/nses/6d.html#es).
- temperature sensor
- clear plastic food container without lid
- plastic wrap (large enough to cover the container)
- rubber band
- awl or scissors (to make a hole in plastic container)
- dirt
- clock
- Caution: Do not look directly at the sun or a sun lamp as eye damage will result.
- Care should be taken while punching the hole in the plastic food container with the awl or scissors so no injury will result.
- Obtain a clear plastic food container without a lid. Any size and shape container will do as long as the container’s width is larger than the metal portion of the temperature probe. The container shown just happens to be round.
- Place a small amount of dirt in the bottom of the container.
- Have an adult punch a small hole halfway up the side of the plastic food container. Place the temperature sensor through the side of the container.
- Prepare a clear plastic wrap cover that will be held on by a rubber band.
Ordinary glass or clear plastic will transmit light but absorb infrared radiation. Knowing this, predict what will happen to the temperature under these two conditions:
a) container in sunlight without the cover;
b) container in sunlight with the plastic cover.
Draw your prediction on the graph below. Imagine that you will collect temperature data in sunlight for 20 minutes. For the first 10 minutes the container will have no cover. For the second 10 minutes the container will be covered with plastic. If you are indoors, the sun will be replaced by a bright light. Make the same prediction for that situation. You will need to move the time axis to include 1200 seconds (20 minutes) by clicking and dragging on the axis.
- Place your container outside in direct sunlight or inside under a bright light.
- Collect temperature data for 10 minutes with no cover.
- Cover the container with plastic wrap.
- Continue to collect temperature data for at least 10 more minutes.
- You can repeat the experiment and save more datasets on the same graph, using the buttons on the left.
- How did the temperature change inside your container with no cover?
- What caused the change in temperature, if any?
- How did the temperature change after the cover was put on?
- What caused the change in temperature, if any?
- How is this situation like the atmospheric “greenhouse effect”? How is it different?
Try the same experiment with a light-colored material in the container, such as sand or sugar or salt. Does it make a difference? Why?
- How would the readings change throughout a complete day (24 hours)?
- What if the surface was more reflective? You were using a dark (dirt) surface, now try a light (sugar) surface.
- What would happen if you added other materials to your container like plants or pollutants, etc.?
- How would an atmosphere of another color affect the temperature within the container?
By using a temperature sensor, we can relate changes in sunlight to the temperature of the air being trapped in a container.
How is the atmosphere like a greenhouse?
The greenhouse effect is the name scientists use to describe how heat can build up in the earth’s atmosphere.
A majority of the energy from the sun arrives at the earth as visible radiation. This energy passes through our atmosphere and warms the surface of the earth. The warmed surface re-emits radiation but this radiation is not visible as it is in the infrared. Some of this infrared radiation is absorbed by our atmosphere. Our atmosphere absorbs more of the infrared radiation when water vapor, carbon dioxide, and methane are present. The more readily the infrared is absorbed, the greater the net energy gain from sunlight.
The effect of this process was examined using a model in the Greenhouse gases activity. In this activity you will measure the phenomenon in a real greenhouse setting. A glass enclosure — a real greenhouse — works in the same way as the atmosphere to capture heat from sunlight.
This activity addresses NSES standards for earth and space science and inquiry at grades 5-8
(http://books.nap.edu/readingroom/books/nses/6d.html#es).
- temperature sensor: see
- clear plastic food container without lid
- plastic wrap (large enough to cover the container)
- rubber band
- awl or scissors (to make a hole in plastic container)
- dirt
- clock
- Caution: Do not look directly at the sun or a sun lamp as eye damage will result.
- Care should be taken while punching the hole in the plastic food container with the awl or scissors so no injury will result.
- Obtain a clear plastic food container without a lid. Any size and shape container will do as long as the container’s width is larger than the metal portion of the temperature probe. The container shown just happens to be round.
- Place a small amount of dirt in the bottom of the container.
- Have an adult punch a small hole halfway up the side of the plastic food container. Place the temperature sensor through the side of the container.
- Prepare a clear plastic wrap cover that will be held on by a rubber band.
Ordinary glass or clear plastic will transmit light but absorb infrared radiation. Knowing this, predict what will happen to the temperature under these two conditions:
a) container in sunlight without the cover;
b) container in sunlight with the plastic cover.
Draw your prediction on the graph below. Imagine that you will collect temperature data in sunlight for 20 minutes. For the first 10 minutes the container will have no cover. For the second 10 minutes the container will be covered with plastic. If you are indoors, the sun will be replaced by a bright light. Make the same prediction for that situation. You will need to move the time axis to include 1200 seconds (20 minutes) by clicking and dragging on the axis.
- Place your container outside in direct sunlight or inside under a bright light.
- Collect temperature data for 10 minutes with no cover.
- Cover the container with plastic wrap.
- Continue to collect temperature data for at least 10 more minutes.
- You can repeat the experiment and save more datasets on the same graph, using the buttons on the left.
- How did the temperature change inside your container with no cover?
- What caused the change in temperature, if any?
- How did the temperature change after the cover was put on?
- What caused the change in temperature, if any?
- How is this situation like the atmospheric “greenhouse effect”? How is it different?
Try the same experiment with a light-colored material in the container, such as sand or sugar or salt. Does it make a difference? Why?
- How would the readings change throughout a complete day (24 hours)?
- What if the surface was more reflective? You were using a dark (dirt) surface, now try a light (sugar) surface.
- What would happen if you added other materials to your container like plants or pollutants, etc.?
- How would an atmosphere of another color affect the temperature within the container?
How does energy change from one form to another?
In this activity energy will be moved from batteries to holiday bulbs and resistors, and the temperature changes will be monitored.
When you use a flashlight, several energy transformations take place. List all of the forms of energy that are involved when you connect a battery to a light bulb. What forms of energy are in the battery, the wires, and the bulb? Where does the energy go at the end of the process?
- Temperature sensor (fast response)
- AA 1.5 V battery and wires
- Battery holder or rubber band
- One holiday light or similar small light bulb
- 10 Ohm resistor (to be heated)
- Small lump of modeling clay. Note:
- 1 Tablespoon of clay = ~28 g
- 1 teaspoon of clay = ~9 g
- Aluminum foil
- Clear tape
- Set up a circuit with a battery, wires, and a light bulb. Check that it works but leave it disconnected.
- Obtain a 10 Ohm resistor that can be substituted for the light bulb in your circuit.
- Attach the temperature sensor directly against the bulb with a piece of clear tape.
- Prepare a piece of aluminum foil just big enough to surround the bulb – about the size of a large postage stamp.
- Prepare a small lump of clay about the size of a marble.
- Make a drawing of your circuit.
You will measure how fast the light bulb heats up when you connect it to the battery, under various conditions. Picture a graph where you turn on the bulb for 30 seconds, then turn it off for 30 seconds. Here are the four conditions:
A. by itself, with just the clear tape holding on the temperature sensor.
B. surrounded by aluminum foil.
C. buried in a lump of clay.
D. The final test will be to heat up a resistor that is buried in a lump of clay, along with the temperature sensor.
For condition A, draw how you think the temperature graph will look, using the graph prediction tool. Then describe in words how the other three graphs will be different from this.
- Attach the temperature sensor to a light bulb with a piece of tape.
- Connect the bulb to a 1.5 V battery. If you don’t have a battery holder, you can use a rubber band.
- Connect the temperature sensor.
- Start data collection.
- Connect your circuit so that the light bulb goes on. Leave it on for exactly 30 s. Disconnect the light bulb and record the temperature for another 30 s.
- Describe this graph. What does the curve look like during the periods when the bulb is on and off?
- Note the starting temperature, the rise during 30 s, and the drop during the next 30 s.
- Let the bulb cool off until it is close to room temperature. Wrap it loosely with a small piece of aluminum foil.
- Start another dataset collection using the buttons on the left.
- Repeat steps 5, 6, and 7.
- What forms of energy does the light bulb produce?
- What happens to the light energy when the bulb is not enclosed in foil, and when it is enclosed in foil?
- Compare the rate heating and cooling of the light bulb with and without the foil. How are they different? Why?
- What can you conclude about whether light bulbs give off mostly heat energy or mostly light energy? Why?
- What happens to the heating and cooling rate when the light bulb is put into a lump of clay? Why?
- How does heating by this light bulb compare to heating by a 10 Ohm resistor?
What can you conclude about whether light bulbs give off mostly heat energy or mostly light energy? Why?
Try other ways of enclosing the light bulb. Turn it on and off for a fixed time and compare the rates of heating and cooling.
How does energy change from one form to another?
In this activity energy will be moved from batteries to holiday bulbs and resistors, and the temperature changes will be monitored.
When you use a flashlight, several energy transformations take place. List all of the forms of energy that are involved when you connect a battery to a light bulb. What forms of energy are in the battery, the wires, and the bulb? Where does the energy go at the end of the process?
- Temperature sensor (fast response). To build the sensor, see:
- “Thermocouple – probe construction”: http://itsidiy.concord.org/activities/392/sail_jnlp/6/13
- AA 1.5 V battery and wires
- One holiday light or similar small light bulb
- 10 Ohm resistor (to be heated)
- Small lump of modeling clay. Note:
- 1 Tablespoon of clay = ~28 g
- 1 teaspoon of clay = ~9 g
- Aluminum foil
- Clear tape
- Set up a circuit with a battery, wires, and a light bulb. Check that it works but leave it disconnected.
- Obtain a 10 Ohm resistor that can be substituted for the light bulb in your circuit.
- Attach the temperature sensor directly against the bulb with a piece of clear tape.
- Prepare a piece of aluminum foil just big enough to surround the bulb – about this size of a large postage stamp.
- Prepare a small lump of clay about the size of a marble.
- Make a drawing of your circuit.
You will measure how fast the light bulb heats up when you connect it to the battery, under various conditions. Picture a graph where you turn on the bulb for 30 seconds, then turn it off for 30 seconds. Here are the four conditions:
A. by itself, with just the clear tape holding on the temperature sensor.
B. surrounded by aluminum foil.
C. buried in a lump of clay.
D. The final test will be to heat up a resistor that is buried in a lump of clay, along with the temperature sensor.
For condition A, draw how you think the temperature graph will look, using the graph prediction tool. Then describe in words how the other three graphs will be different from this.
- Attach the temperature sensor to a light bulb with a piece of tape.
- Connect the bulb to a 1.5 V battery. If you don’t have a battery holder, you can use a rubber band.
- Connect the temperature sensor.
- Start data collection.
- Connect your circuit so that the light bulb goes on. Leave it on for exactly 30 s. Disconnect the light bulb and record the temperature for another 30 s.
- Describe this graph. What does the curve look like during the periods when the bulb is on and off?
- Note the starting temperature, the rise during 30 s, and the drop during the next 30 s.
- Let the bulb cool off until it is close to room temperature. Wrap it loosely with a small piece of aluminum foil.
- Start another dataset collection, using the buttons on the left.
- Repeat steps 5, 6, and 7.
10.
11. Repeat steps 2 – 6.
- What forms of energy does the light bulb produce?
- What happens to the light energy when the bulb is not enclosed in foil, and when it is enclosed in foil?
- Compare the rate heating and cooling of the light bulb with and without the foil. How are they different? Why?
- What can you conclude about whether light bulbs give off mostly heat energy or mostly light energy? Why?
- What happens to the heating and cooling rate when the light bulb is put into a lump of clay? Why?
- How does heating by this light bulb compare to heating by a 10 Ohm resistor?
What can you conclude about whether light bulbs give off mostly heat energy or mostly light energy? Why?
Try other ways of enclosing the light bulb. Turn it on and off for a fixed time and compare the rates of heating and cooling.