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: ), ['o study the relationship between the temperature of a hot body and time by plotting a cooling, UTE. i, ratus : A thimble or calorimeter, constant temperature enclosure, a thermometer, stop clock, hot :, water bath etc., jton’s law of cooling :, dO |, The rate of fall of temperature | — by a body is directly proportional to the difference of |, temperature (6 -6,) of the body over the surroundings, provided the difference is small. |, |, , Diagram :, , , , <———--——_ Thermometer, ¢——— Stirrer, , Lid, , Water, , Calorimeter, >,, , Le Doubled walled, YW | \<— container, , , , , , , , , , r ite at which a hot body loses heat is directly proportional to the difference between the, temperature of the hot body and that of its surroundings and depends on the nature of material and the |, surface area of the body. This is newton’s low of Colling, , Rate of loss of heat a =k(@-6,), - Eh = i, Where, K = is the constant of proportionality K = <, , Scanned with CamScanner

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Note down the temperature of the surrounding (room temperature) by using thermometer., , , , : Bhi ee :, Fill the thimble or calorimeter with hot water about 75 to 80°C upto Fr th of its capacity. Insert, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , 3., thermometer such that its bulb is well inside the hot water., 4. Note the initial temperature which is about 750 to 80°C above the room temperature., 5. start the stop watch., 6. Note the temperature after every minutes., | 7. Take required number of readings till temperature of water falls about 40°C., | 8. Plot the graph of temperature (6°,C) against time (t) in minutes. Draw smooth curve through the, points., 9. Plot the graph of ° against temperature @.Hence determine the room temperature (8,)., 10. Plot a graph of rate of cooling against excess temperature above the surrounding Hence verify, Newton’s law of cooling., Observations :, 1. Least count of stop watch = ee ee S., 2. Least count of thermometer = --!------- 20., 3. Temperature of the surrounding (6) = 30. 0c., Observation Table (I) :, Ob. No. Time in min Temperature of | Ob. No. Time in min Temperature of, water °C water °C, ; ° 33 ne Is 5), ite h 78 us 16 et 49g, E 2 75 o I? 49, i 3 Ea 2 ig “a4, S o 40 20 19 4g, g 5 6g zi 20 46, q a 65 22 2} ye, 8 7a 63 23 22 a5, 9 g s] a 2g 4g, 10 Jd 5q 25 ay 45 46, WZ lo BL 26 25 48, Tio ') 5G 27 yy 42, 13 12 55 28 ay Wye., 14 1g) BI 29 2° ao., 15 1y as 30 29 a6, , , , , , , , , , , , , , , , , , , , , , , , Notebook of Physci:, , , , Std XII / 14, , , , Scanned with CamScanner