A) 10 : 1
B) 2 : 1
C) 10 : 9
D) 9 : 1
Correct Answer: B
Solution :
Illuminance on the screen without mirror is \[{{I}_{1}}=\frac{L}{{{r}^{2}}}\] Illuminance on the screen with mirror \[{{I}_{2}}=\frac{L}{{{r}^{2}}}+\frac{L}{{{r}^{2}}}=\frac{2L}{{{r}^{2}}}\] Þ \[\frac{{{I}_{2}}}{{{I}_{1}}}=2:1\]You need to login to perform this action.
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