UNIVERSITY OF ILORIN, NIGERIA

DEPARTMENT OF PHYSICS

PHY491: REPORT ON

HEAT CONDUCTION EXPERIMENT

BY

IDOWU ABDULSAMAD AYOMIDE

20/56ED049
TITLE: HEAT CONDUCTION
AIM: To Determine the difference in the rate conduction through bars of
different material and cross-sectional areas.
INTRODUCTION:
The heat conduction experiment aims to explore how thermal energy transfers
through various materials. Heat conduction refers to the movement of thermal
energy from a higher temperature region to a lower temperature region within a
substance. In this experiment, a metal rod or similar solid material is usually
heated at one end, and temperatures are recorded at different points along its
length over time.

Apparatus
The heat conduction apparatus as four metal bars(1 aluminum, 1 stainless steel, 2
brass with different cross sections).Each bar has two 10kOhms thermistors
embedded in it about 3 cm apart from each other. Two mercury-in-glass
thermometer is used in taking measurement5 of temperature at point T1 to T8 on
the bars. The apparatus has a thermoelectric module with a switch to change the
DCV being applied to it for a "Heat" or "Cool" option.

EXPERIMENT 1: HEAT CONDUCTION RACE

Procedure:
1. Adjust Power Supply:
o Set the power supply to a 5V DC output.
2. Connect Power to Apparatus:
o Use two banana patch cords to connect the power supply to the Heat
Conduction device.
3. Measure Thermistor Positions:
o Measure the distance between the two thermistors embedded in each
bar. The locations are indicated by white lines on the apparatus
board.
4. Create a Layout Diagram:
o Draw a diagram showing the arrangement of the apparatus,
including the Peltier device, the four bars, and the thermistors.
Label the thermistors as follows:
T1: Wide Brass (far end)
T2: Wide Brass (near end)
T3: Narrow Brass (near end)
T4: Narrow Brass (far end)
T5: Aluminum (far end)
T6: Aluminum (near end)
T7: Stainless Steel (near end)
T8: Stainless Steel (far end)
5. Switch to Heat Mode:
o Set the apparatus switch to HEAT and place the insulators over the
bars to retain heat.
6. Check Initial Temperature:
o Use an infrared thermometer to verify that all bars are at room
temperature before starting the experiment.
7. Take Temperature Readings Over Time:
o Record the temperature at each of the thermistor points (T1 to T8)
for all four bars every 60 seconds, up to a total of 5 minutes.
8. Graph Temperature vs. Time:
o Plot a graph of temperature vs. time for the “far” thermistor points
(T1, T4, T5, and T8).
9. Calculate Temperature Difference (ΔT):
 o Calculate the temperature difference (ΔT) between the "close" and
"far" thermistors for each bar:
ΔT = T(close) - T(far) o Perform this calculation for
each bar and plot the results on a graph.
10. Allow Bars to Cool:
Set the power supply voltage to zero and remove the insulators to let the
bars cool down to room temperature.
READINGS:
Room temperature = 26.3oC
Distance between = 3cm

STABLE 1: TEMPERATURE MEASUREMENT FOR THE ‘FAR’ BARS

Time(s) Wide Brass(℃) Narrow Aluminium(℃) Stainless(℃)
Brass(℃)

T1 T2 T3 T4 T5 T6 T7 T8

60 29.7 32.4 30.0 29.8 30.8 30.9 30.6 30.9

120 30.6 29.8 30.6 30.0 30.8 30.8 31.0 30.8

180 30.7 30.1 30.8 30.4 31.1 30.8 31.2 31.1

240 30.8 32.7 31.0 30.6 31.1 31.4 32.6 31.4

300 31.1 30.3 31.6 30.9 32.1 32.0 32.2 31.9

QUESTIONS
1.The best conductor is Aluminum.
- The stainless. Is the worst conductor
- The wide Brass bar is more of a conductive material than the narrow Brass.

2.Temperature gradient: It refers to the rate of change in temperature with respect

to distance within a material. In the context of the heat conduction experiment,
the temperature gradient is determined by measuring how the temperature
decreases progressively from the heated end of the material to the cooler regions
The peak occurs because each material has different conductivity.

3. ΔT (Wide Brass) = 2.7°C ΔT (Narrow Brass) =

0.7°C
ΔT (Aluminum) = 0.7°C
ΔT (Stainless) = 1.5°C

4. Heat flow rate ΔQ/Δt for Wide Brass: Since ΔQ/Δt

= kAΔT/x
= 115 (W/m-k) x 0.09 (m) x 0.012 (m) x 275 (k)
0.032 (m)
= 1067.34 J/s

Heat flow rate ΔQ/Δt for Narrow Brass: Since ΔQ/Δt = kAΔT/x
= 115 (W/m-k) x 0.090 (m) x 0.007 (m) x 275 (k)
0.032 (m)
= 622.84 J/s

Heat flow rate ΔQ/Δt for Aluminum: Since ΔQ/Δt = kAΔT/x

= 150 (W/m-k) x 0.090 (m) x 0.012 (m) x 274 (k)
0.032 (m)
= 1387.12 J/s
Experiment 2: Heat Pulse Procedure:
1. Preparation:
o Ensure that all four bars are at room temperature before starting the
experiment.
o Record the initial temperatures of the bars (denoted as T1 and T2).
2. Heating Phase:
o Set the switch to HEAT and place insulators over the bars to
minimize heat loss.
o Adjust the power supply to 5V DC and start taking measurements of
the temperatures T1 and T2 simultaneously.
o Record the temperatures at 30-second intervals for a total of 60
seconds.
3. Switching to Cooling:
o Once the temperature measured by T2 reaches approximately
40°C, change the switch to COOL mode to begin cooling the bars.
o Start timing using a clock or stopwatch.
o Alternate the switch between HEAT and COOL every 30 seconds,
continuing this cycle for a total of 60 seconds (30 seconds heating
and 30 seconds cooling).
4. Data Collection:
o Continue alternating the heating and cooling phases for several
minutes until the temperature waveform stabilizes and reaches a
constant amplitude. The temperature fluctuation should become
consistent after a few cycles.
5. Completion:
o Once the temperature waveform stabilizes, stop your data collection.

o Turn the power supply to 0V to stop heating and cooling.

TABLE 2: HEAT PULSE FOR WIDE BRASS

Time(s) T1 T2

60 30.8 31

120 32.2 32.7

180 33.3 34.2

240 31.9 32

300 34 33.1

360 34.7 34

420 32.9 32.7

480 31.6 32.7

540 32.4 34

600 32.2 33.7

660 32 32.9
Questions
1. The temperature fluctuation forms a triangular waveform. As the heat reaches
the far thermistor T1, the temperature increases, reaching its peak value before
beginning to cool down.
2. Time lag is caused by the time it takes heat to travel through a material, the
time lag is 360 seconds.
3. The amplitude change is because the rate of temperature increase might be
slightly different due to factors like thermal conductivity changes with
temperature. No, the waves are actually similar.

32.5

31.5

30.5

120 180 240

30.8 30.8 31.1 31.1 32.1
30.9 30.8 30.8 31.4

5. The aluminum bar wave shape shows an upward movement which shows that
it is a good conductor. Aluminum is a better conductor than brass
6. The time lag in aluminum is 300 sec which is lower than that of brass. This
means the speed of pulse in aluminum is faster than that in brass.

PRECAUTION
Maintained a constant power supply of 5V throughout the experiment.
Verified that all metal bars were at room temperature before initiating the
experiment.
Refrained from touching the Peltier device and metal bars during operation to
avoid interference.
Measured the initial room temperature of each metal bar to account for any
variations.
Monitored the device’s temperature during power application to ensure optimal
performance.