A `5 W` source emits monochromatic light of wavelength `5000 Å`. When placed `0.5 m` away , it liberates photoelectrons from a photosensitive metallic surface . When the source is moved to a distance of `1.0 m` the number of photoelectrons liberated will be reduced by a factor of

Options

A. be reduced by a factor of 2
B. be reduced by a factor of 4
C. be reduced by a factor of 8
D. be reduced by a factor of 16

Answer

2

Explanation

`I prop (1)/(r^(2))`
No of electrons emitted `prop` Intensity (I).