Light is the prime factor in the human life as all activities of human beings ultimately depend upon the light. Where there is no natural light, use of artificial light is made. Artificial lighting produced electrically, on account of its cleanliness, ease of control, reliability, steady output, as well as its low cost, is playing an increasingly important part in [...]
There are two laws of illumination: 1. Law of Inverse Squares 2. Lambert's Cosine Law. 1. Law of Inverse Squares: If a source of light which emits light equally in all directions be placed at the centre of a hollow sphere, the light will fall uniformly on the inner surface of the sphere, that is to say, each square mm [...]
In an arc lamp electric current is made to flow through two electrodes in contact with each other which are drawn apart. The result is an arc being struck. The arc maintains the current, and is very efficient source of light. There are various forms of arc lamps such as carbon-arc, flame-arc or magnetic-arc lamps. Type # 1. Carbon-Arc Lamp: [...]
In this article we will discuss about:- 1. Filament Materials Used in Incandescent Lamps 2. Filament Dimensions of Incandescent Lamps 3. Types 4. Aging Effects 5. Effects of Voltage Variations. Filament Materials Used in Incandescent Lamps: For sometimes the arc lamps were used for general lighting purpose but as the carbon-arc lamps were complicated so these have been superseded by [...]
The fluorescent lamp in common with most electrical devices may cause a certain amount of radio interference. This interference may be caused due to one of the following factors: 1. Direct radiation from the bulb to the antenna. This effect diminishes rapidly as the radio is separated from the lamp. Thus, for example, at a radius of 2.8 metres interference [...]
In this article we will discuss about:- 1. Principle of a Gaseous Discharge Lamp 2. Types of Gaseous Discharge Lamps 3. Drawbacks. Principle of a Gaseous Discharge Lamp: The basic principle of a gaseous discharge lamp is illustrated in Fig. 7.32. Gases are normally poor conductors, especially at atmospheric and higher pressures, but application of suitable voltage, called the ignition [...]
In this article we will discuss about the determination of candle power of a lamp. Use of Polar Curves to Determine the Candle Power of a Lamp: It is assumed that the luminous intensity or the candle power from a source is uniformly distributed over the surrounding surface. But none of the practical type of lamp provides light uniformly distributed [...]
The lighting scheme should be such that it may: (i) Provide adequate illumination, (ii) Provide light distribution all over the working plane as uniform as possible, (iii) Provide light of suitable colour, and (iv) Avoid glare and hard shadows as far as possible. The following factors are required to be considered while designing the lighting scheme: Factor # 1. Illumination [...]
Floodlighting means flooding of large surfaces with light from powerful projectors. Purpose of Floodlighting: It is employed to serve one or more of the following purposes: 1. Aesthetic Floodlighting: For enhancing beauty of building at night such as public places, ancient buildings and monuments, religious buildings on important festive occasions etc. 2. Industrial and Commercial Floodlighting: For illuminating railway yards, [...]
Adequate lighting of factories is of vital importance, as it provides improved amenities for the employees, increased production and has a definite economic value in reducing accidents with their consequent loss of time and compensation payments. General Requirements and Types of Installations for Factory Lighting: A factory lighting installation, in common with other indoor equipments should provide an adequate illumination [...]