GK-12 Sensors!
Portable Module

Title: Heat Transfer by Conduction and Radiation

Author: Aaron Clark

Disciplines: Physical Science, Physics

Introduction

This module introduces students to concepts involving heat transfer by conduction and radiation. Conduction involves the transfer of heat by the interaction of adjacent molecules of a material. Radiation heat transfer is concerned with the exchange of thermal energy between two bodies via electromagnetic radiation; no medium is needed between the two bodies for heat transfer to take place (as is needed for conduction). This module should be used as a supplement to a lesson on heat transfer.

Heat lamps of course can become very hot and can cause injury or burn flammable material. Students should be supervised closely, use proper protective equipment, and keep a safe distance from the heat lamps.

Associated Maine Learning Results

SCIENCE AND TECHNOLOGY

H. ENERGY
Students will understand concepts of energy.
Students will be able to:
3. Compare and contrast the ways energy travels (e.g., waves, conduction, convection, radiation).

J. INQUIRY AND PROBLEM SOLVING:
Students will apply inquiry and problem-solving approaches in science and technology.
Students will be able to:
1. Make accurate observations using appropriate tools and units of measure.
2. Verify, evaluate, and use results in a purposeful way. This includes analyzing and interpreting data, making predictions based on observed patterns, testing solutions against the original problem conditions, and formulating additional questions.

K. SCIENTIFIC REASONING:
Students will learn to formulate and justify ideas and to make informed decisions.
Students will be able to:
3. Develop generalizations based on observations.
4. Determine when there is a need to revise studies in order to improve their validity through better sampling, controls or data analysis techniques.
5. Produce inductive and deductive arguments to support conjecture.

I. COMMUNICATION
Students will communicate effectively in the application of science and technology.
Students will be able to:
4. Employ graphs, tables, and maps in making arguments and drawing conclusions.

Required Equipment

Per lab group:

• Lab stands (4)


• Clamps and clamp holders


• Heat lamp with clamp on fixture


• Electronic temperature sensors or thermometers (2)


• Metal plate (approximately 12” x 12”,~1/16” thick, painted black)


• Aluminum foil—radiant barrier

Procedure

Set-up:

Use two lab stands to suspend the metal plate perpendicularly (one on each side with clamps close to top of metal plate to reduce heat transfer to the stands). Set up the heat lamp about 12 inches from the metal plate (directed at the center of the plate). Affix temperature sensor to the center of the back of the metal plate (opposite side of lamp). Place the other temperature sensor ¾” away from the back of plate (near the center but not directly behind the other temperature sensor). Allow at least five minutes after set-up for the plate and sensors to reach ambient temperature.

Experiment:

1. Take one plate and one air temperature measurement with the lamp off, then turn the lamp on and take additional plate and air temperature measurements every minute for five to ten minutes.
2. Turn off lamp and allow plate to cool back to ambient temperature—a fan can speed up the process. If there are enough metal plates for two plates per group that would eliminate waiting almost entirely. If metal plates are in short supply, have students work on data analysis between experiments.
3. Cover side of metal plate with aluminum foil which faces the heat lamp. Repeat steps one and two.
4. Cover side of metal plate with aluminum foil which faces away from the heat lamp. Repeat steps one and two.
5. With temperature readings from each temperature sensor for all three experiments, the students should have two sets of data to graph, analyze, compare and discuss.
   

Expected Results

With a brief lesson on heat transfer preceding this activity, students should be able to distinguish the two types of heat transfer they are observing during the experiments. Before conducting the experiments the students should be able to make reasonable predictions about what they expect to observe. Students should produce a graph of their data for each temperature sensor which they can analyze, discuss, and compare with their predictions.


Observations should include:

• The plain metal plate has the highest rate of temperature increase and highest end temperatures for both the plate and air temperature measurements.
• The plate temperature of the radiant barrier facing back away from the lamp ends up much higher than the plate temperature of the radiant barrier facing the lamp. This result is because the radiant barrier facing the lamp reflects radiation back to the lamp keeping the plate surface cool (so there is little conduction through the plate), while in the case where the radiant barrier faces away from the lamp the plate is heated by the lamp and the heat conducts through the plate to the radiant barrier and then to the temperature sensor affixed to it.
• The air temperatures behind the plates for both the radiant barrier facing the lamp and the radiant barrier facing away from the lamp are very similar. This result may be a surprise since the plate temperature of the radiant barrier facing away from the lamp is much higher than the case where the radiant barrier faces the lamp, but a radiant barrier reflects radiated heat and also is a poor radiation emitter even when the material itself heats up, so again little heat is re-radiated or emitted to the temperature sensor ¾" behind the plate.
  

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