Question
Download Solution PDFA lamp of 80 watt with efficiency of 80% of watt/CP is suspended, The illumination at a point on a working plane directly below the lamp is 25 lumens/m2. Determine the height at which the lamp is suspended?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept
To determine the height at which the lamp is suspended, we can use the formula for illumination (illumination intensity) at a point on a working plane, which is given by:
\(E={I\over d^2}\)
where, E = Illumination in lux (lumens/m²)
I = Luminous intensity in candelas (CP)
d = Distance from the lamp to the point (height of the lamp in meters)
Calculation
Given, E = 25 lumens/m2
P = 80 watt
Efficiency = 80% of watt/CP
\(0.8={80\over CP}\)
CP = 100
\(E={I\over d^2}\)
\(d^2={100\over 25}\)
d = 2 m
Last updated on May 29, 2025
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