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

A Battery-operated Torch is Adjusted to Send an Almost Parallel Beam of Light. It Produces an Illuminancle of 40 Lux When the Light Falls on a Wall 2 M Away. - Physics

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MCQ
Fill in the Blanks

A battery-operated torch is adjusted to send an almost parallel beam of light. It produces an illuminancle of 40 lux when the light falls on a wall 2 m away. The illuminance produced when it falls on a wall 4 m away is close to _________ .

Options

  • 40 lux

  • 20 lux

  • 10 lux

  • 5 lux

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Solution

40 lux

 

Since the beam is parallel, it will have no angular spread. So the illuminance will remain same throughout. Therefore, in this case, it will be 40 lux.

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
MCQ | Q 6 | Page 454
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