WBSETCL Junior Engineer Electrical Grade II 14th March 2022 First Shift Solution

Harikesh Yadav
WBSETCL Junior Engineer Electrical Grade II 14th March 2022 First Shift Solution PDF
Question : 1

A room of 12 m length and 10 m breadth is lighted by 15 lamps to a fairly uniform illumination of 100 Im/m2. Calculate the utilisation coefficient of the room given that the output of each lamp is 1600 lumens.

A. 80%
B. 60%
C. 90%
D. 50%
Answer-D
Solution

Given A = 12 m × 10 m

Total lamps = 15 lamps

Each lamp output = 1600 lumens

Illumination E = 100 lm/m2

Total lumens reaching the working plane = 100 × 12 × 10 =12000 lumen

Total lumen emitting from source = 1600 × 15 = 24000 lumen
Utilization Coefficient=total lumens reaching the working plane/total lumens emitting from source

Utilization Coefficient=12000/24000 = 0.5 or 50%

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