OBJECT: To investigate the relationship between the pressure and temperature of a constant volume of gas.
METHOD: A mass of dry air is trapped above a column of mercury in a closed tube immersed in water. The closed tube forms one arm of a mercury manometer. The pressure upon the confined air, and hence its volume, can be regulated by means of a plunger in a mercury reservoir. The value of the pressure is obtained from the difference between the mercury levels in the open and closed arms of the manometer. The temperature of the water bath is altered and a series of observations is made upon the pressure of the confined gas, its volume being maintained constant.
Continue reading ‘Expansion of Gases’
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I. INTRODUCTION: Observations are taken in the laboratory and from these observations certain conclusions are drawn. Since no observation or series of observations is absolutely accurate, it is often desirable to check the dependability of the conclusions by a study of the errors in the experiment.
Suppose that an experiment on the relation between the pressure and volume of a gas is performed in the laboratory and that the conclusion is the statement of the law that the volume is inversely proportional to the pressure. The experiment does not prove that the law is absolutely accurate but only that within certain limits, determined by the accuracy of the experiment, it has been found to be true. Small departures from the law will always be found and it should be possible to determine whether these departures indicate that the law is not exactly true or whether they are due to unavoidable experimental errors. Even if in this experiment no significant departures were found, observations with more refined apparatus might show conclusively that the law was only an approximation to the truth.
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OBJECT: To study energy transformations in multiple collisions of objects on a linear air track and to relate the rate of energy change to a Die-away Curve.
METHOD: An object floating on a linear air track is made to collide with several different materials. Upon impact the object rebounds and recollides several times, reaching a particular height for each rebound. Heights of successive rebounds are measured, and the coefficients of restitution are computed. Next, Die-away Curves are drawn from these data to show the rate of energy transformation. The curves then are related to other decay processes.
Continue reading ‘Energy Transformations in Multiple Collisions (Linear Air Track)’
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OBJECT: To determine by means of a photometer the relationship between the efficiency of an incandescent lamp and the potential drop across it.
METHOD: A standard lamp and a test lamp are placed at opposite ends of a photometer bench. By adjusting the position of a photometer box so that its screen is equally illuminated on the two sides, the candle power of the test lamp is determined. This is repeated for various voltages on the test lamp and the relationship between the voltage and efficiency (candles per watt) determined.
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OBJECT: To investigate the effect upon the period of a vibrating system caused by varying its mass, and to make a determination of the mass of a body by a dynamical method.
METHOD: An elastic system is so arranged that its mass can be varied. The period is observed for a number of (known) masses and a curve is plotted of the mass versus the square of the period. A body of unknown mass is then added and its mass determined from observations of the period. This dynamically determined mass is then compared with the corresponding mass obtained by weighing.
Continue reading ‘Dynamical Comparison of Masses’
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OBJECT: To measure the wavelength of light with a diffraction grating.
METHOD: A slit in an opaque screen, illuminated with a sodium flame or other source of bright line spectrum, is viewed through a diffraction grating held near the eye. With the rulings of the grating parallel to the slit, several orders of spectra are seen on either side of the slit. The various spectral images are located by means of a transverse scale mounted beside the slit. From the known value of the grating space and from the measured distances between the slit and the grating and between the slit and the successive spectra, the wavelength of light is calculated.
Continue reading ‘The Diffraction Grating’
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OBJECT: To determine the density of a liquid and of a solid, using the pycnometer method.
METHOD: The mass of an irregular solid is determined by weighing. When the solid is placed in a pycnometer (Fig. 1) filled with a liquid of known density, the volume of the liquid which will overflow is equal to the volume of the solid. The mass of the liquid which will overflow is determined as the difference between the sum of the mass of the pycnometer filled with liquid plus the mass of the solid and the mass of the pycnometer filled with liquid after the solid has been placed inside. The volume occupied by this mass is determined from the known density of the liquid. It is necessary that the solid be insoluble in the liquid used. The density of the solid is determined from these measurements of mass and volume.
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OBJECT: To determine from the dimensions and the mass of a: cylinder the density of the material of which the cylinder is composed.
METHOD: Using a micrometer caliper, a number of observations are made of the diameter and of the height of a cylinder. From the average value obtained for each of these dimensions the volume of the cylinder is computed. The mass of the cylinder is determined by weighing it on a balance. The ratio of the mass of the cylinder to its volume is the density of the material.
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OBJECT: To determine the densities of a solid and a liquid by using Archimedes’ principle and a Jolly balance.
METHOD: A body is alternately weighed suspended in air and immersed in a liquid. The apparent loss in weight of the immersed body is known, by Archimedes’ principle, to equal the weight of liquid displaced by the body. The apparent less in weight is measured by means of a spring. From these measurements the density and specific gravity of either the solid body or the liquid may be determined.
Continue reading ‘Densities of Solids and Liquids Using a Jolly Balance’
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OBJECT:
- Part I: To determine the density of two solids, one of which is heavier and the other lighter than an equivalent volume of water.
- Part II: To measure accurately the density of various liquids by means of the Westphal balance.
- Part III: To measure the specific gravity of these liquids by means of a hydrometer.
METHOD: A body is weighed in air and then immersed in a liquid. The apparent loss in weight of the body when immersed in the liquid is, by Archimedes’ principle, equal to the weight of liquid displaced by the body. From these measurements the density and specific gravity of either the solid body or the liquid may be determined.
Continue reading ‘Densities of Solids and Liquids’
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