Illuminating Engineering Practice: Lectures on Illuminating Engineering Delivered at the University of Pennsylvania, Philadelphia, September 20 to 28, 1916McGraw-Hill Book Company, Incorporated, 1917 - 578 halaman |
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Halaman 7
... beam and reaching a maximum of 1.0 in the case of a source of uniform candle - power such as a spherical surface source . It may be well at this point to call attention to the fact that the " mean spherical candle - power " of a surface ...
... beam and reaching a maximum of 1.0 in the case of a source of uniform candle - power such as a spherical surface source . It may be well at this point to call attention to the fact that the " mean spherical candle - power " of a surface ...
Halaman 92
... beam than it is to obtain one with a beam of moderately great angle , well distributed and concentrated , but progress is now being made to assure good results in almost any condition that can be found . I will not here go at length ...
... beam than it is to obtain one with a beam of moderately great angle , well distributed and concentrated , but progress is now being made to assure good results in almost any condition that can be found . I will not here go at length ...
Halaman 93
... beam at the expense of the primary closely directed beam . They thus may throw light over an angle of 90 ° or so and cannot give high concentration , although showing very low intrinsic brilliancy and having a distinctly useful place in ...
... beam at the expense of the primary closely directed beam . They thus may throw light over an angle of 90 ° or so and cannot give high concentration , although showing very low intrinsic brilliancy and having a distinctly useful place in ...
Halaman 94
... beam falls on the required surface distance does not count save as it may involve atmospheric absorption which is of small moment at flood- lighting distances . Only when the spread of the beam gets it off the object does distance ...
... beam falls on the required surface distance does not count save as it may involve atmospheric absorption which is of small moment at flood- lighting distances . Only when the spread of the beam gets it off the object does distance ...
Halaman 126
... beams equally directed about the periphery of the lamp . The two mirrors are employed to obviate the violent flicker on the photometer disc which would otherwise occur . PHOTOMETRY OF LAMPS WITH SHADES AND REFLECTORS The measurement of ...
... beams equally directed about the periphery of the lamp . The two mirrors are employed to obviate the violent flicker on the photometer disc which would otherwise occur . PHOTOMETRY OF LAMPS WITH SHADES AND REFLECTORS The measurement of ...
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ILLUMINATING ENGINEERING PRAC University of Pennsylvania,Illuminating Engineering Society Pratinjau tidak tersedia - 2016 |
Istilah dan frasa umum
accessories ęsthetic amount amperes angle application artificial light artistic average beam bowl bowl type brightness bulb burner candle candle-power distribution carbon ceiling cent church color considerable cost curve dark daylight decorative density desirable direct lighting distance effect efficiency electric electrodes enamel equipment factor filament fixtures foot-candles gas mantle gas-filled give glare glass glassware horizontal important incandescent lamps indirect installation integrating sphere intensity interior lecture light flux light sources lighting units lumens luminous luminous arc luminous flux Magnetite mantle Mazda measure method mirror obtained opal operating photometer photometry plane practical prismatic produce proper reflection Reflection Coefficient reflectors screen screw semi-indirect shades shadows shown in Fig solid angle space specular reflection sphere spherical standard street lighting sufficient surface test-plate tion Trans tungsten lamps uniformity usually vision VOLT walls watt window yellow
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Halaman 37 - Symbols. — In view of the fact that the symbols heretofore proposed by this committee conflict in some cases with symbols adopted for electric units by the International Electrotechnical Commission, it is proposed that where the possibility of any confusion exists in the use of electrical and photometrical symbols, an alternative system of symbols for photometrical quantities should be employed. These should be derived exclusively from the Greek alphabet, for instance: Luminous intensity r Luminous...
Halaman 32 - I, of a point source of light is the solid angular density of the luminous flux emitted by the source in the direction considered; or it is the flux per unit solid angle from that source. Defining equation: . da or, if the intensity is uniform, fwhere u> is the solid angle.
Halaman 31 - K,,,, over any range of wave-lengths, or for the whole visible spectrum of any source, is the ratio of the total luminous flux (in lumens) to the total radiant power (in ergs per second, but more commonly in watts).
Halaman 35 - Mean horizontal candle-power of a lamp, — the average candlepower in the horizontal plane passing through the luminous center of the lamp. It is here assumed that the lamp (or other light source) is mounted in the usual manner, or, as in the case of an incandescent lamp, with its axis of symmetry vertical.
Halaman 112 - When auxiliary devices are necessarily employed in circuit with a lamp, the input should be taken to include both that in the lamp and that in the auxiliary devices. For example, the watts lost in the ballast resistance of an arc lamp are properly chargeable to the lamp. 889 The Specific Consumption of an electric lamp is its watt consumption per lumen. " Watts per candle " is a term used commercially in connection with electric incandescent lamps, and denotes, watts per mean horizontal candle-power.
Halaman 191 - In perfect diffuse reflection, the flux is reflected from the surface in all directions, in accordance with Lambert's cosine law. In most practical cases, there is a superposition of regular and diffuse reflection.
Halaman 33 - Brightness, b, of an element of a luminous surface from a given position, is the luminous intensity per unit area of the surface projected on a plane perpendicular to the line of sight, and including only a surface of dimensions negligibly small in comparison with the distance to the observer. It is measured in candles per square centimeter of the projected area.
Halaman 33 - For most purposes, the millilambert (0.001 lambert) is the preferable practical unit. A perfectly diffusing surface emitting one lumen per square foot will have a brightness of 1.076 millilamberts.
Halaman 34 - Coefficient of diffuse reflection is the ratio of the luminous flux reflected diffusely to the total incident flux. Defining equation: Let m be the coefficient of reflection (regular or diffuse). Then, for any given portion of the surface, E' m"H
Halaman 32 - Phot." One millilumen per square centimeter (milliphot) is a practical derivative of the cgs. system. One foot-candle is one lumen per square foot and is equal to 1.0764 milliphots. The milliphot is recommended for scientific records.