Let be the maximum kinetic energy of photoelectrons emitted by light of wavelength `lambda_(1)` and `lambda_(2)` correspondingto wavelength `lambda_(2)`. If `lambda_(1) = 2lambda_(2)` then:

Options

A. `2K_(1) = K_(2)`
B. `K_(1) = 2K_(2)`
C. `K_(1) lt K_(2)//2`
D. `K_(1) gt 2K_(2)`

Answer

C

Explanation

`K_(1) = (hc)/lambda_(1) -W`……. (i)
and `K_(2) = (hc)/lambda_(2) - W`…….. (ii)
Substituting `lambda_(1) = 2lambda_(2)` in Eq. (i), we get
`K_(1) = (hc)/(2lambda_(2)) - W`
`=1/2((hc)/lambda_(2)) - W = 1/2(K_(2) +W) -W`
`therefore K_(1) = K_(2)/2 - W/2` or `K_(1) lt K_(2)/2`