A) 10 %
B) 20%
C) 27%
D) 36%
Correct Answer: D
Solution :
\[{{I}_{1}}=\frac{L}{r_{1}^{2}}=\frac{L}{1600}\] and \[{{I}_{2}}=\frac{L}{2500}\] \ % decease in illuminance \[=\frac{{{I}_{1}}-{{I}_{2}}}{{{I}_{1}}}\times 100\]\[=\left( 1-\frac{1600}{2500} \right)\times 100\]\[=\frac{900}{2500}\times 100=36\]You need to login to perform this action.
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