ConductionEXPERIMENT ON HEAT TRANSFER

Objectives

To be able to understand the premise of conduction, its concepts and theories

To show how heat transfer happens in conduction using the different materials

To be able to compare conduction with other forms of heat transfer like convection and radiation

Theory

The operating equation that we’re going to use is:

where Q= heat transferred in time

K= thermal conductivity of the barrier

A= Area

T= Temperature

= Thickness

CONDUCTION FORMSTHE SIMPLE ACT OF FRYING IN A PAN IS ALREADY A FORM OF CONDUCTON HEAT TRANSFER

How The Laboratory Set-up Would Look LikeAn experiment which demonstrates different metals have different conductivity

Materials

Four rods different materials (copper, brass, iron, aluminum.) We have to make sure that the rods have the same diameter.

Several rods of the same material but of different diameters

Box of colored birthday candles

Ring stand (or block of wood or brick for resting the heated rods)

Hot plate with known Voltage and Current Conditions

Metric ruler

Watch or clock with

Graph paper

Procedure

• Label each rod (A, B, and C, D) • Using a metric ruler, mark off one-centimeter increments on the rods.

• Using graph paper, make a data table with an entry for each rod. 

• Turn on the hot plate. We’re looking for ways to make sure that the heat will be isolated towards the rod.

• Put the candles on the marks on the rods.

• Place one end of one of the rods on the edge of the hotplate, balancing the other end on the wood block

• Time how long it takes for the heat to travel down the rod, recording the time when it melts the drops of wax.

• Repeat with each of the other rods.

• Make a graph with time versus distance to record the information from the data table.

• Make a list indicating which rod was the best conductor and which rod was the poorest conductor.

• Calculate for K.

METHOD:

Since we will be having 4 rods of different materials in this experiment. We will do the set-up two at a time so we can have a better comparison of the data. Two rods of the same size, one made of aluminum and one of brass, are heated by the same lighter at one end. Candles are stick evenly along both rods. Starting from the heated end, these candles would fall one by one as the heat conducted through the rods is sufficient to melt the base of the candles. An earlier time of fall thus indicates that the metal is a better conductor of heat.

The next 2 other metals will be made of copper and iron.

DISCLAIMER: We are comparing metals because comparison of conductivity is already apparent in metals vs wood, or metals vs plastic.

ECONOMICS

Four rods different materials - Buy each , estimate at P60.00 each * 4 = P240.00

Box of colored birthday candles – P50.00

Ring stand – available in the lab

Hot plate with known Voltage and Current Conditions - Lab or nothing

Metric ruler – Lab or we provide

Watch or clock with – Individual

Graph paper – P10.00

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TOTAL = P300.00

Analysis of Data

Room temperature to the temperature at which the rods are being subjected to, which in this case is the temperature of the hot plate, can easily be measured. Thickness of the area of subjection as well as the time it took to get to that melting process are measurable quantities. Heat conduction of materials are known so the thermal conductivity can be calculated.

P = V^2/R = Qinput

Thickness to use = distance from one end to burnt wax in 5 minutes

T(hot) = T(heat source), Making sure steady source of heat at constant T

T(cold) = Room temperature

A = R^2 of the rod

Time = 5 minutes