Answered: An unknown lamp placed 6m from a…

An unknown lamp placed 6m from a photometer screen provides the same illuminance as a 90 cd lamp placed 4 m from the screen. What is the candlepower of the unknown lamp?

Sustainable Energy

2nd Edition

ISBN:9781337551663

Author:DUNLAP, Richard A.

Publisher:DUNLAP, Richard A.

Chapter19: Battery Electric Vehicles (bevs)

Section: Chapter Questions

Problem 8P

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1. An unknown lamp placed 6m from a photometer screen provides the same illuminance as a 90 cd lamp placed 4 m from the screen. What is the candlepower of the unknown lamp?

2. The illuminance of a room 20 ft x 15 ft is being designed. The illuminance required is 50 footcandles. What is the total required lumens output of the lamp assuming room and luminaire efficiency of 42%?

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