Warmth Capacity Against a Period of Time - Research Paper Example

LABORATORY 2: HEAT Name Student Number Course: Module: Professor Information Date of Experiment: Date of Submitting the Report: Abstract A resistor connected to a source of power generates energy that is in form of heat. By recording this rise in temperature and the corresponding time at various intervals, a graph of temperature versus time is drawn. This trend line represents change in temperature divided by change in time. Since both temperature and time increases with increase in time, specific heat capacity of the metal rod is obtained by plugging values from the experiment into the equation. On the other hand, thermal conductivity of a metal can be deduced by arranging an experiment using heat source, metal, thermometers, and heat sink was. A record of temperature rise of heat sink is taken until sink attains target temperature,. Values obtained are inserted into the equation and rearranged to give thermal conductivity of the metal under investigation. Table of Contents Abstract 3 Introduction 5 Theory 5 Method 6 Results 7 Discussion and Analysis 10 Conclusion 12 Reference List 13 Appendices 14 Introduction This paper is a report of an experiment done to establish specific heat capacity and thermal conductivity of metals. The first part of the experiment aims at finding specific heat capacity of an unknown metal. A metal of known resistance connected to a source of power generates heat. The rise in temperature and the corresponding time in seconds are recorded and used in calculation of specific heat capacity. In the second part of the experiment, thermal conductivity of unknown metal is investigated using an assembly of heat source, metal, thermometers, and heat sink. Values obtained from both experiments are compared with known standard values in order to understand potential cause of the discrepancies. Theory Current flowing through a resistor converts electrical energy to heat. This power generated as electric current flowing through a resistor is calculated using the equation: . Besides, power is the change in energy divided by change in time: In a research conducted by Myers (2006, p.86), heat, specific heat capacity, and change in temperature have a relationship established by the equation:. Q is the thermal energy often referred to as heat in joules, m is mass in grams, and c is the specific heat capacity. Change in temperature is represented by and is the final minus initial temperatures. The equation of thermal energy shows that as energy increase with time, the temperature also increases with time. This results in a relationship given by: Fourier’s law gives a relationship that exists in thermal conduction. According to this law, rate of heat flow and temperature gradient are related. The law gives a direct relationship between heat flow between two surfaces and temperature gradient and area. This is shown by the equation: (Thirumaleshwar, 2006). It therefore means that thermal conductivity is equals to rate of heat flow through a given area of one square meters of a 1 m think rod with temperature kept at 1 degrees celcius. Method In the first part of the experiment, heating element was connected to power supply set at a voltage of 23 Volts. Current through the resistor and voltage drop across the resistor was measured and tabulated on a table. Connecting heating bock H1 to source of heat had the effect of raising temperature of the block. The rise in temperature of the heated block H1 was recorded within an interval of a few seconds. Using the results of temperature rise and time, a graph of temperature versus time was drawn. A line of best fit, given by , was obtained from the graph of temperature versus time. In the second part, heating element was connected to source of power by setting voltage supply at 23 Volts. Heated element was allowed to attain a temperature of . Heat source H1, unknown metal M1, thermometers, and heat sink was assembled for experiment. A thermometer was attached to both sides of M1 and heat sink S1. A record of temperature rise of heat sink was taken until S1 attained. This data was later used to draw a graph of temperature versus time. When conducting the experiment, precaution was taken in reading temperatures and time because they respond very fast. The second risk in the experiment was exposing heating devise to the air for a long time. Poor handling of thermometers further presented the risk of giving wrong temperatures. Results Part 1: Temperature and time Time (s) Temperature (°C) Time (s) Temperature (°C) 0 18 270 35 15 18 285 36 30 19 300 37 45 20 315 38 60 21 330 39 75 21 345 41 90 22 360 42 105 23 375 43 120 24 390 44 135 25 405 45 150 26 420 46 165 28 435 47 180 29 450 47 195 30 465 48 210 31 480 48 225 32 495 49 240 33 510 49 255 33 525 49 Part 2: Temperature and time Time θ1 (°C) θ2 (°C) S1 (°C) θ1 (°C) θ2 (°C) S1 (°C) 0 32 22 19 840 40 33 15 34 23 19 855 40 33 30 35 23 19 870 40 33 45 35 24 19 885 40 34 60 36 24 19 900 40 34 75 36 25 19 915 40 34 90 36 25 19 930 40 34 105 37 26 20 945 40 34 120 37 26 20 960 40 34 135 37 27 20 975 40 34 150 37 27 20 990 40 34 165 38 27 21 1005 40 34 180 38 27 21 1020 40 34 195 38 28 21 1035 40 34 210 38 28 21 1050 40 35 225 38 28 21 1065 40 35 240 38 28 22 1080 40 35 255 38 28 22 1095 41 35 270 38 28 22 1110 41 35 285 38 28 22 1125 41 35 300 38 29 22 1140 41 35 315 38 29 23 1155 41 35 330 38 29 23 1170 41 35 345 38 29 23 1185 41 35 360 38 29 23 1200 41 35 375 38 29 23 1215 41 36 390 38 29 24 1230 41 36 405 38 30 24 1245 41 36 420 38 30 24 1260 41 36 435 38 30 24 1275 41 36 450 38 30 24 1290 41 36 465 38 30 25 1305 41 36 480 38 30 25 1320 41 36 495 38 30 25 1335 41 36 510 39 30 25 1350 41 36 525 39 31 25 1365 41 36 540 39 31 26 1380 41 36 555 39 31 26 1395 41 36 570 39 31 26 1410 41 36 585 39 31 26 1425 41 36 600 39 31 26 1440 41 36 615 39 31 26 1455 41 36 630 39 32 26 1470 41 37 645 39 32 27 1485 41 37 660 39 32 27 1500 41 37 675 39 32 27 1515 41 37 690 39 32 27 1530 41 37 705 39 32 27 1545 42 37 720 39 32 28 1560 42 37 735 40 32 28 1575 42 37 750 40 33 28 1590 41 37 765 40 33 28 1605 41 37 780 40 33 28 1620 42 37 795 40 33 28 1635 42 37 810 40 33 28 1650 42 37 825 40 33 28 1665 42 38 Discussion and Analysis Part 1 Table 1 clearly shows that temperature is rising as time increase. This observation is also visible in a chart of temperature versus time, figure 1. In the figure of temperature versus time, line of best fit is represented by At the beginning of the experiment, voltage was set at 23 Volts. Given that resistance was 4.7 ohms, heat dissipation rate, Q, in watts is calculated as: This is likely to be sodium metal with specific heat capacity of 1.23. Error: Part 2 Tabulated results showed that temperature in the sink increased in the same manner with time. Plotting a graph of temperature versus time gives figure 2 below. Points: Gradient of tangent: Heat flow through the rod in Watts: At point p, temperature difference is: This metal is most likely to be: Conclusion Through the experiment, thermal conductivity and specific heat capacity of unknown metals was obtained. However, the experimental values deviated from perceived actual values by some percentages. These deviations are attributed to measurement and estimation errors. Thermometers are sensitive to environment and time such that any laxity in reading temperature and time culminates into errors. Reference List Myers, R. L 2006, The basics of physics, Westport: Greenwood Publishing Group. Thirumaleshwar, M 2006, Fundamentals of Heat and Mass Transfer. New Delhi, Pearson Education. Appendices Read More