A.C. carbon arc lamp :
Working principle :
Two carbon rods kept face to face touching to each other connected to the source of electricity and if they are departed from each other to form a small air gap between them, an arc is produced with tremendous heat and a light is produced.
V. = (39 + 2.8 1) where l: length of arc in mm
10% of light by negative carbon
5% of light by the air.
Uses of Arc lamps :
For Next part
Working principle :
Two carbon rods kept face to face touching to each other connected to the source of electricity and if they are departed from each other to form a small air gap between them, an arc is produced with tremendous heat and a light is produced.
Construction and working is similar to D.C. type.
- The difference is only instead of D.C. supply A.C. supply is connected and instead of a controlling resistance (R) a controlling reactor (L) is connected as shown in the following figure.
- In its case burning of both positive and negative rod is same and hence their cross section area is same in A.C. operation.
- Since the carbon is consumed during operation frequent adjustment for the gap between rods is required.
- An automatic device is provided for feeding the carbon into the arc for big lamps.
V. = (39 + 2.8 1) where l: length of arc in mm
- A series resistance or reactor as shown in the figure is used for stabilizing the arc.
- Overall is luminous efficiency very low 12 lumens/watt.
- In A.C. arc lamp, instead of a series resistance, inductor is used for stability.
- % production of light :
10% of light by negative carbon
5% of light by the air.
- Temperature :
Uses of Arc lamps :
- Cinema projectors
- Search lights
For Next part