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Photometry and Luminous Intensity - Class VIII
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A lamp placed 60 cm from a screen produces the same illumination as a standard 100 W lamp placed 90 cm away on the other side of the screen. The luminous intensity of the first lamp is
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A
$44.44W$
💡 Explanation:
For same illumination $\dfrac{Power} { r^{2}}$ will be same
=> $\dfrac {100} { 0.9^{2}} = \dfrac {P} {0.6^{2}}$
=> P = $44.44 W$