## 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 20

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**tion**at the central point , P , would be βα = c ( da ) r2 ( 2 ) From simple geometrical relations , the correctness of which will be appreciated at once from a glance at Fig . 13 , it is seen that the areas ( da ) and ( dA ) bear to ... Halaman 28

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**tion**, but rather the production of adequate average illumination without excessive brightness in the field of view . PRESENT DAY CALCULATING METHODS The adoption of the method of 28 ILLUMINATING ENGINEERING PRACTICE. Halaman 29

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**tion**, converts the calculations of the lighting expert from those of the physicist to those of the engineer . Just as the mathematical physicist will continue to deal with fictitious isolated magnetic poles and by careful ... Halaman 31

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**tion**, may be expressed in terms of 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 ... Halaman 38

... ) and add 10 per cent . to this sum , the result will be the total lumens in the zones under considera-

... ) and add 10 per cent . to this sum , the result will be the total lumens in the zones under considera-

**tion**. The quick way to get this sum is. Fig . 1. - Polar coordinate candle - power curve . 38 ILLUMINATING ENGINEERING PRACTICE.### Edisi yang lain - Lihat semua

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.