Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 12

# A Source Emits 31.4 W of Radiant Flux Distributed Uniformly in All Directions. the Luminous Efficiency is 60 Lumen Watt−1. What is the Luminous Intensity of the Source? - Physics

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Sum

A source emits 31.4 W of radiant flux distributed uniformly in all directions. The luminous efficiency is 60 lumen watt−1. What is the luminous intensity of the source?

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#### Solution

Given that,

Radiant flux = 31.4 W

Since the radiant flux is distributed uniformly in all directions, the solid angle will be 4π Luminous efficiency = 60 lumen/W

So, luminous flux = luminous efficiency × radiant flux

= 60 × 31.4 lumen

Luminous intensity = "Luminous flux"/"Solid angle"="Luminous flux"/(4pi)

=(60xx(31.4))/(4pi)

= 150 candela

Concept: Light Process and Photometry
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#### APPEARS IN

HC Verma Class 11, Class 12 Concepts of Physics Vol. 1
Chapter 22 Photometry
Exercise | Q 8 | Page 455
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