A) \[\sqrt{10}m\]towards the screen
B) \[(5+\sqrt{10})m\]towards the screen
C) \[(5-\sqrt{10})m\]towards the screen
D) \[(5-\sqrt{10})m\]away from the screen
E) \[\sqrt{10}\]away from the screen
Correct Answer: C
Solution :
\[E\propto \frac{5}{{{5}^{2}}}\]and \[E=\frac{2}{{{x}^{2}}}\] But \[E=E\] \[\Rightarrow \] \[x=\sqrt{10}\,m\] To get same illuminance the remaining lamps should be moved\[(5-\sqrt{10})m\]towards the screen.
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