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Two lamps of illuminating powers 25 cd a...

Two lamps of illuminating powers 25 cd and 100 cd are placed at the end of a photometer bench 2.0 m long. At what point on the bench will the screen of the photometer be equally illuminated on both sides.

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The correct Answer is:
0.67 m for 25 cd lamp
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SL ARORA-RAY OPTICS-Problems For Self Practice
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