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.
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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.
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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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