复旦大学：《大学物理——热学》课程教学资源（PPT课件）第3次课

大学物理(热学) 金晓峰 复旦大学物理系 xijin@fudan.edu.cn 2006-9-13 2021/9/5

2021/9/5 1 大学物理（热学） 金晓峰 复旦大学物理系 xfjin@fudan.edu.cn 2006-9-13

FIGURE 17-12 Pressure vs volume of a gas at a constant temperature, showing the inverse relationship as given by Boyle's law: as the pressure increases the volume decreases

) 73℃ rC°C000X10×20K30X40K50K

Constant-volume gas thermometer Reference mark Mercury Bulb Connecting ose FIGURE 17-7 Constant-volume gas thermometer

FIGURE 17-14 Blowing up a balloon means putting more air (more air molecules) into the balloon. which increases its volume The pressure is nearly constant (atmospheric) except for the small effect of the balloons elasticity

Scale Gas-filled bulb Fig- 18-5A constant-volume gas thermometer. its bulb immersed in a liquid whose temperature T is to be measured

Gas thermometer 4.58 torr Ice 273.16K Water Fig. 18-4 A triple-point ce which solid ice, liquid water, and water vapor coexist in thermal equi librium. By international agreement the temperature of this mixture has been defined to be 273.16 K. The bulb of a constant-volume gas ther mometer is shown inserted into th well of the cell

4.58 torr 273.16 K

37400 37380 37360 373.40 373.2O He 3730 0200400600800100O tp(torr) FIGURE 17-15 Temperature readings of a constant-volume gas thermometer for the boiling point of water at loo atm are plotted, for different gases, as a function of the gas pressure in the thermometer at the triple point (Ptp ote that the amount of gas in the thermometer is reduced so that tp O, all gases give the same reading, 373.15 K. For pressure less than o.lo atm (6 torr), the variati shown is less than O07 K

GRIN thermometer bulb 273.16K 37400 Water 373.8 Fig. 18-4 A triple-point cell. in 373.6O which solid ice. liquid water and water vapor coexist in thermal equi- 373.40 the temperature of this mixture has librium. By international agreemen 373.2O been defined to be 273.16 K. The 373.00 bulb of a constant-volume gas ther- O2004006O08001000 mometer is shown inserted into the Ptp(torr) well of the cell FIGURE 17-15 Temperature readings of a constant-volume gas thermometer for the boiling point of water at l oo atm are plotted. for different gases, as a function of the gas pressure In e thermometer at the triple point ). Note that ceats-hillect the amount of the thermomete educed. so that →O,a1 s give the same reading.373 373.15K Fig. 18-5A constant-volume gas thermometer. its bulb immersed in a liquid whose temperature is to be measured

273.16 K 373.15 K

gas moving about in a cubical of a FIGURE 18-1 (a) Molecules container. (b) Arrows indicate the momentum of on molecule as it rebounds from the end wall (a) (b)