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A point source kept at a distance of 100...

A point source kept at a distance of 1000 m has a illumination I. To change the illumination to 16I, the new distance should become

A

250 m

B

500m

C

750 m

D

800 m

Text Solution

Verified by Experts

The correct Answer is:
B
`(I_(2))/(I_(1)) = ((r_(1))/(r_(2)))^(2)`
`(161_(1))/(I_(1))=(1000)^(2)/(r_(2)^(2)),r_(2)=(1000)/(4)=250 m`
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