18: Experimental Measurements
- Page ID
- 7332
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 18.1: Introduction
- This page discusses the historical neglect of experimental measurements in heat and thermodynamics, linking it to personal interests. It contrasts reliance on modern technology with the challenging yet precise classical experiments of the 19th and early 20th centuries. The author highlights the significance of these early experiments and their contributions to understanding thermal quantities, emphasizing their accuracy achieved through careful design despite their seemingly crude methods.
- 18.2: Thermal Conductivity
- This page covers the measurement of thermal conductivity in solid conductors and fluids, detailing experiments such as Searle's Rod for metals, which measure heat flow via temperature differentials. It discusses advancements in measurement techniques, including thermocouples, and adaptation for non-metals using disc shapes.
- 18.3: The Universal Gas Constant
- This page covers the measurement of ideal gas properties, focusing on the relationship between pressure (P), temperature (T), and volume (V) through the equation PV = RT. It highlights the straightforward measurement of P and T and the complexities of gauging volume.
- 18.4: Avogadro's Number and Boltzmann's Constant
- This page discusses Avogadro's number and its determination via electrolytic deposition, showcasing the relationship between a faraday (approximately 96,484 coulombs) and a mole of monovalent elements. It introduces Boltzmann's constant as the ratio of the ideal gas constant (R) to Avogadro's number (NA), and hints at a forthcoming definition of these constants expected in 2015.
- 18.5: Specific Heat Capacities of Solids and Liquids
- This page explains the method of mixtures for measuring specific heat capacities of materials through calorimetry, focusing on temperature changes rather than absolute values. It mentions Joule's experiments, which were crucial in establishing the mechanical equivalent of heat, and presents advanced techniques like electrical heating that reduce heat losses for more accurate measurements.
- 18.6: Specific Heat Capacities of Gases
- This page covers the measurement of specific heat capacity for gases at constant pressure and volume. It details Regnault's 1860 experiments using gas cooling and water warming for specific heat calculation, emphasizing the need for precision. It also describes Joly's 1890 differential steam calorimeter, which employs copper spheres and steam condensation for volume measurement. Both methods are noted for their straightforward principles but demand high experimental skill for accurate results.
- 18.7: Latent Heat of Fusion
- This page explains a procedure to measure the specific latent heat of ice using a calorimeter. It details how dropping ice into warm water causes temperature changes, which can be calculated to determine latent heat. Key considerations include minimizing heat loss and accounting for residual water on the ice. The Bunsen Ice Calorimeter is emphasized as a precise tool, utilizing mercury levels to accurately gauge the amount of ice melted through temperature and volume changes.
- 18.8: Coefficient of Expansion
- This page details various techniques for measuring the coefficient of thermal expansion in materials such as rods, plates, and liquids. It explains the use of measuring microscopes for rods, interference fringes for flat plates, comparisons with quartz for cubes, and a weight thermometer for nonvolatile liquids. Additionally, it describes a U-tube method for comparing liquid densities at different temperatures to calculate expansion coefficients.