01․ Illumination can be expressed in
Light is the cause and illumination is the effect of light on which it falls i.e., when light falls upon the surface, this process is called illumination. It is given as no. of lumen falling on a surface per unit area. It is expressed in lux or meter candle.
02․ Luminous efficacy of a typical HPSV lamp is in between
The typical lumen package of a HPSV lamp is 8000 lumens and its power rating is 70-150W.
03․ Total flux or lumens required in any lighting scheme depends inversely on
All the light emitted by the source does not reach the surface to be illuminated. Some of light directly falls on the surface some of the light reaches the surface and some of light never reaches the surface to be illuminated as it is getting absorbed.
04․ Wave length for red colour is around
Red colour lies at the extreme right hand side end of the visual spectrum. So its wavelength is highest than any other colour.
05․ Unit of luminous flux is
Luminous flux is defined as the total quantity of the light energy radiated or emitted per second from a hot body in the form of light waves. It is measured in lumens.
06․ Which of the following statement is correct?
Light is nothing but a electromagnetic radiation which causes visual radiation to the eye.
07․ Luminous efficiency of a fluorescence lamp is
Luminous efficiency is defined as the ouput in lumens per watt of the power consumed by the source of the light. For fluorescence lamp luminous efficiency is 40 lumens / watt.
08․ The illumination of the surface varies directly with cosine of the angle between normal to surface and direction of the inclined light is given by
According to Lambars cosine law the illumination of the surface varies directly with cosine of the angle between normal to surface and direction of the inclined light.
09․ ___________________________ factor is defined as the ratio of the illumination when everything is clean to illumination under normal working conditions.
Due to the accumulation of the dirt, dust and smoke on the lamps they emits less light as compared to when they are new. Similarly walls and ceiling they reflect less light when are cover with dust. Hence to design a source of light we need to consider the depreciation factor. It is usually greater than 1.
10․ The work of ballast in a fluorescent tube is to
Ballasts are basically inductors which protect the lamp from excessive current and also gives the bulb a kickstart when voltage is induced in the coil.