Electrical Illumination Tutorials and Its Engineering Definition

Light 

The light is defined as the energy radiated in the form of waves which produces the sensation of vision to the eyes. It may be natural light from sun or the artificial from the means created by human beings.

Lumen

It is the unit of luminous flux and is defined as the luminous flux emitted per unit solid angle by a point source of one candle power.

Brightness 

The brightness is defined as the luminous intensity per unit projected area of either a source of light or reflecting surface. It is denoted by B and the unit is stib which is nothing but candle per centimeter squared, other unit is nit which is candle per meter squared.

Coefficient of Utilization

It is defined as the ratio of the lumens  actually received by a particular surface to the total lumens emitted by the luminous source. The coefficient of utilization or the utilizing factor is the total lumens actually received by the working plane per total lumens emitted by the light source.

Candle Power 

The candle power is the light radiating capacity of a source in a given direction. It is defined as the number of lumens given out by a source in a unit C.P. and one meter away from it.

Colour

The sensation of colour is due to the difference in the wavelengths of the light radiations. Visible light can have length between 4000 A to 7500 A and colour varies in the way.

Luminous Intensity

The luminous intensity in any given direction is the luminous flux emitted by a source per unit solid angle. It is represented by I and measured in candle power.

Luminous Flux 

It is the total quantity of light emitted by the source of light per second. It is represented by symbol O or F. It is measured in lumen. The total flux emitted by a source of I candle is 4 pi times I lumen where I is the luminous intensity of the source.

Some Characteristics of a good Illumination

1. The light source should not strike the eyes of the worker.
2. The type and size of the lamp should be correct.
3. Location should be proper.
4. Reflecting equipment should be suitable.

The Advantages of Correct Illumination

1. Factory production increases
2. Accidents decrease
3. Wastage of jobs decreases.

The sources of light is Three practicable ways of producing light are incandescent of heated filament  and electric are glow discharge.   Where the incandescent filament lamp is the light obtained by passing, current through a high resistance called the filament, this current being sufficient to raise the filament to luminosity. The filament is enclosed in an evacuated glass bulb. The object of the vacuum is first to prevent the filament burning away to reduce loss of heat by convection. The filament must be a conductor and must be capable of withstand a hight temperature.