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Heat Transfer Experiment: Measuring Thermal Conductivity in Various Materials, Lab Reports of Physics

An experiment designed to help students gain experience with heat transfer through conduction and radiation. Students will measure the coefficient of thermal conductivity for different materials, determine their r factors, investigate the construction of a thermos bottle, and measure the relative degree of heat transfer by radiation for four different coated surfaces. The experiment involves melting ice using steam and measuring the resulting mass and temperature changes, as well as using a radiation cube to measure voltage and draw conclusions about radiation emission.

Typology: Lab Reports

Pre 2010

Uploaded on 07/30/2009

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koofers-user-0t9 🇺🇸

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Physics 2A
Heat Transfer
Introduction
This experiment is designed to give you more experience with heat transfer through the mechanisms of
conduction and radiation. Specifically, you will:
1. Measure the coefficient of thermal conductivity for one of several different materials.
2. Determine the R factor for these materials.
3. Measure the relative degree of heat transfer by radiation for four different coated surfaces, each
with a different coating (black, metallic grey, white and polished metal).
4. Investigate the construction of a thermos bottle (or Dewar flask) by measuring the rate of cooling
of four different bottles, each with a different feature (or features) that are all found in the common
thermos bottle.
You should review heat transfer (see text and lecture notes) before beginning.
Part 1: Conduction
Experiment
12
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Physics 2A

Heat Transfer

Introduction

This experiment is designed to give you more experience with heat transfer through the mechanisms of conduction and radiation. Specifically, you will:

  1. Measure the coefficient of thermal conductivity for one of several different materials.
  2. Determine the R factor for these materials.
  3. Measure the relative degree of heat transfer by radiation for four different coated surfaces, each with a different coating (black, metallic grey, white and polished metal).
  4. Investigate the construction of a thermos bottle (or Dewar flask) by measuring the rate of cooling of four different bottles, each with a different feature (or features) that are all found in the common thermos bottle. You should review heat transfer (see text and lecture notes) before beginning.

Part 1: Conduction

Experiment

Procedure

  1. Fill the ice mold with water and freeze it. One or two drops of a non-sudsing detergent in the water before freezing will help the water to flow more freely as it melts and will not significantly effect the results. These molds are usually prepared for you and can be obtained from the stockroom.
  2. Measure and record the thickness of the sample material (L) using a cm caliper.
  3. Mount the sample material onto the steam chamber as shown in the figure. Take care that the sample material is pushed against the water channel, so water will not leak, and then tighten the thumbscrews lightly. Use a small amount of grease between the channel and the sample, as shown in the figure, to create a good watertight seal.
  4. Place the ice on top of the samples (as shown in the figure). It is not necessary to remove the ice from the mold. Just place the open end of the mold against the sample, and let the ice slide out as the experiment proceeds.
  5. Let the ice sit for several minutes so it begins to melt and comes into full contact with the sample. Do not take data before the ice begins to melt, because it may be at a lower temperature than 0 C. Now slip off the plastic mold and measure the diameter of the ice cylinder in several locations with the cm caliper, average them and record this average as d 1.
  6. Obtain data for determining the ambient melting rate of the ice as follows a. Mass a small container and record. b. Collect the melted ice in a beaker for a measured time (ta) using a stopwatch. This time should be close to 10 minutes. c. Mass the beaker and the water and record. d. Subtract your second measured mass from your first to determine mwa (the mass of the melted ice).
  7. Run steam into the steam chamber. Let the steam run for several minutes until the temperature stabilizes and the heat flow is steady.
  8. Repeat step 6 with steam running into the steam chamber. Measure and record m (^) w (the mass of the melted ice), and t (the time during which the ice melted), which should be from 5 - 10 minutes.
  9. Re-measure the diameter of the ice block as before and record the value as d 2.
  10. When you are finished, return the remaining ice to the mold (do not discard), fill with water, and return it to the stockroom.

Part 2: Radiation

The Radiation Cube

Locate the radiation cube (do not touch the coated sides), the radiation detector and a voltmeter. Connect the detector to the voltmeter and turn on the light bulb inside the cube. You can now activate the detector by pushing down on the metallic strip (do not use the clamp ring), and as you bring it up to one of the sides (prong distance), a voltage can be read from the meter (only activate the detector when you want to make a reading). After the cube has reached equilibrium (about 5 min.), measure the voltage for all four sides and record them below as a measure of the relative radiation emitted.

TABLE 3

Coated Side Voltage (V) Ratio to Silver

Silver

Grey

White

Black

Conclusions

  1. What kind of radiation is the detector measuring?

  1. What conclusion(s) can you draw (besides the obvious comparison) from the above results?


  1. Why do some desert dwelling tribes wear black, while other tribes wear white?



Part 3: Conduction, Convection & Radiation

The Thermos Bottle (or Dewar Flask)

The construction of this device illustrates all three methods of heat transfer. Explain below how the thermos minimizes heat transfer.





Procedure

Locate the four thermos bottles with one-hole stoppers and the digital thermometer. Inspect these bottles carefully and describe them below. Bottle A: _______________________________________________________________ Bottle B: ________________________________________________________________ Bottle C: ________________________________________________________________ Bottle D: ________________________________________________________________ Fill the four bottles with hot water (approximately 85 C) allowing enough room to insert the one- hole rubber stoppers. Start the timer and measure and record the initial temperatures of all four bottles as quickly as you can. After two minutes, measure and record the four temperatures again in the same order as before. Continue this procedure, measuring and recording the temperatures every two minutes for a total time of twenty minutes.

Bottle A Bottle B Bottle C Bottle D

Time T (  C) Time T (  C) Time T (  C) Time T (  C)