A photocell is placed at 1 m distance from light source when distance is changed to `(1)/(2)`m no.of photoelectron emitted from cathode will come

Options

A. become 2 times
B. decreases by factor of 2
C. becomes 4 times
D. decreases by factor of 4

Answer

C

Explanation

`"intensity" prop(1)/(("distance from source ")^(2)) `
`therefore I prop (1)/(d^(2)) therefore (I_(2))/(I_(1))=((d_(1))/(d_(2)))^(2)`
From `d_(2)=(d_(1))/(2)`
`(I_(2))/(I_(1))=(2)^(2)=4` intensity becomes four times.