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DMRC JE EE 2018 Official Paper 2

Option 3 : 0.9

CT 1: Basic Concepts

18461

10 Questions
10 Marks
6 Mins

**Concept:**

Coefficient of utilization or utilization factor is given by:

\(utilization\;factor = \frac{{total\;lumens\;reaching\;the\;working\;plane}}{{total\;lumens\;emitting\;from\;source}}\)

**Calculation:**

Given A = 12 m × 12 m

Total lamps = 10 lamps

Each lamp output = 1600 lumens

Illumination E = 100 lm/m^{2}

Total lumens reaching the working plane = 100 × 12 × 12 =14400 lumen

Total lumen emitting from source = 1600 × 10 = 16000 lumen

Utilization factor = \(\frac{{14400}}{{16000}} =\) 0.9