To demonstrate the difference in thermal conductivity of the three metals, you can proceed differently. Thermal Conductivity of Plastic and Metal I. Comparing Thermal Conductivity of Copper, Aluminium and Brass. In the interpretation of the extension of the experiment, we should be careful not to give the impression that the sheets “sucked” the cold out of the ice – it is always necessary to interpret the temperature decrease as a heat extraction. endstream endobj 94 0 obj <> endobj 95 0 obj <>/Font<>/ProcSet[/PDF/Text/ImageC]/XObject<>>>/Rotate 0/TrimBox[0.0 0.0 504.0 720.0]/Type/Page>> endobj 96 0 obj <>stream It is a measure of a substance’s ability to transfer heat through a material by conduction. If the temperature increases, in the interval from 25 °C to 30 °C the film gradually changes its colour from brown, green and blue to navy blue, and finally after exceeding 30 °C the colour changes back to black. The effect stated above can be eliminated by bending the bottom ends of the sheets to right angle. A successfully performed experiment is illustrated by the video below. Pure aluminum has a thermal conductivity of about 235 watts per kelvin per meter, and an electrical conductivity (at room temperature) of about 38 million siemens per meter. Do not pour boiling water in the container, use water with temperature of 60 °C. Fasten the copper, aluminium and brass sheet parallel to each other (see for example Fig. K −1] Notes Acrylic glass (Plexiglas V045i) 0.170 –0.200: … 237. (W/m K) Aluminum. Choose required ranks and required tasks. Then submerge the ends of the metal sheets in a mixture of water and ice. A table with thermal conductivities (at 25 °C) of used metals is stated below: Thermosensitive film can be found on the internet under the name reversible temperature label. Lay the copper, aluminium and brass sheet on the table and in the middle of each sheet place an ice cube. It is not necessary to use hot water to heat the sheets. Thermal Conductivity of Plastic and Metal II. The argument that fast heating of the copper sheet is caused by its low heat capacity can be easily confuted with the table below: Therefore, if the decisive factor were specific heat capacity of the metal, the behaviour of copper and brass would be almost the same (they have similar values of c), but this is in clear contradiction with the experiment. This thought is correct and should be appreciated – the willingness of matter to change its temperature depends on the specific heat capacity as well as the thermal conductivity of matter. If you perform this experiment in the summer, it is recommended to make sure that the temperature in the classroom is lower than the minimum temperature measured by the film (here 25 °C). h��W�O�8�W�#����j��:�5m���ִ�I�* �����$%)����*rc�~����Q�P�h�C�>��1� ߜe� �|bR�&1M�o���@#�pRp��L�"5h�hÕO�c��TDKðP�� �Q:&�ƅ�E����D4�����-8��=. Heat Dissipation Through a Copper Plate or How to Speed up Cooling of Tea, Melting Point of Sodium Thiosulfate Pentahydrate, Dependence of Boiling Point of Water on Pressure, Writing with Alcohol Based Highlighters and Markers, Dependence of Evaporation Rate of Liquid on Liquid Surface Area, Evaporation of Water and Ethanol (with Thermal Imaging Camera), Dependence of Evaporation Rate of Liquid on Removing Fumes from above Its Surface, When Carbon Dioxide is Lighter Than Air (Temperature Impact on Gas Density), Capillary action between two glass plates. See theory in an already described experiment: Thermal Conductivity of Plastic and Metal I., Theory. The effect of different thermal conductivity can be demonstrated not only with heating the metals, but also with cooling them. This article will explore the mechanisms of heat transfer, what makes metals ideal thermal conductors, and uses of common metals & alloys. The thermal conductivity of a material such as metal is highly dependent on composition and structure. Thermal conductivity (cal/sec)/(cm 2 C/cm) Thermal conductivity (W/m K)* Diamond... 1000: Silver: 1.01: 406.0: Copper: 0.99: 385.0: Gold... 314: Brass... 109.0: Aluminum: 0.50: 205.0: Iron: 0.163: 79.5: Steel... 50.2: Lead: 0.083: 34.7: Mercury... 8.3: Ice: 0.005: 1.6: Glass,ordinary: 0.0025: 0.8: Concrete: 0.002: 0.8: Water at 20° C: 0.0014: 0.6: Asbestos: 0.0004: 0.08: Snow (dry) 0.00026... Fiberglass: 0.00015: 0.04: … The purpose of such colour changing of these films is not to attempt precise temperature measurements at a particular point, but rather to indicate and demonstrate the distribution of surface temperature. The table of contents will list only tasks having one of the required ranks in corresponding rankings and at least one of the required tags (overall). Then submerge the ends of the metal sheets in a mixture of water and ice. The effect of different thermal conductivity can be demonstrated not only with heating the metals, but also with cooling them. The temperature represented by the colour depends on the film type. Metals are typically known to be highly efficient thermal conductors . Thus the longer part of the measured metals can stay in a horizontal position. - t -. h�bbd```b``��i �i!�d;������xD Copper cools down the fastest, followed by aluminium and brass. The film used in this experiment is black at temperatures lower than 25 °C. 0 Thermosensitive film with temperature range from 25 °C to 30 °C, three different metal plates of the same size, container for hot water, kettle. %%EOF Copper has high thermal conductivity and therefore is able to constantly supply heat from the peripheral parts of the sheet to the place cooled by the ice cube. %PDF-1.6 %���� (oC) Thermal Conductivity. Tools and equipment usually found at schools, Thermal Conductivity of Plastic and Metal I., Theory, Change in Internal Energy by Performing Work: Nail Hammering, Conversion of Kinetic Energy into Internal Energy: Blow with a Mallet, Conversion of Kinetic Energy to Internal Energy: Falling Weight, Experimental determination of Specific Heat of Water, Comparing Specific Heat of Water and Vegetable Oil. endstream endobj startxref Figure 1 shows a tool made especially for this experiment to study the different thermal conductivity of metal – three different metal plates are partly covered by a thermosensitive film, which indicates the temperature increase. The advantage of this experiment is the possibility to go without the thermosensitive films. Aluminum alloys can have much lower conductivities, but rarely as low as iron or steel. More proficient students can figure out that we have already discussed the “willingness” of matter to change temperature in the context of specific heat capacity c of matter. Conductive heat … 93 0 obj <> endobj 128 0 obj <>stream The goal of this experiment is to use thermosensitive films to visualize the different dynamics of heat conduction in three different metals. 107 0 obj <>/Filter/FlateDecode/ID/Index[93 36]/Info 92 0 R/Length 85/Prev 181608/Root 94 0 R/Size 129/Type/XRef/W[1 3 1]>>stream 2). The description of the development of this experiment leads the students to a conclusion that “copper heats faster than aluminium” etc. Temperature. If there are truly gifted physicists in the class, they can object that this argument is not entirely satisfactory – the sheets have different density and hence the mass, which affects the size of the heat needed for the heating, is also different. -73. It is apparent that the copper sheet heats the fastest, followed by aluminium and brass. ��z��)�w�b�JEG���IG3���-���l�с� c`�d�y���bF=�@Ɨl���k�GJ�-�"��('��iX�$��g �}x�/)�U!�̕pQY�#�Q�`� w�: However, you always need to ensure that the sheets warm up evenly.