The photoelectric threshold wavelength of silver is `3250 xx 10^(-10) m`. The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength `2536 xx 10^(-10) m` is
`(Given h = 4.14 xx 10^(6) ms^(-1) eVs` and `c = 3 xx 10^(8) ms^(-1))`

Options

A. `= 0.6 xx 10^(6) ms^(-1)`
B. `= 61 xx 10^(3) ms^(1)`
C. `= 0.3 xx 10^(6) ms^(-1)`
D. `= 6 xx 10^(5) ms^(-1)`

Answer

A, D

Explanation

`(h c)/(lambda) = (h c)/(lambda_(0)) + (1)/(2) m v^(2)`
`v = sqrt((2hc)/(m)[(1)/(lambda) - (1)/(lambda_(0))]) "if " lambda (Å)` (given)
`E = (h c)/(lambda) = (12400 eV)/(lambda(Å))Å`
`v = sqrt((2 xx 12400 xx 1.6 xx 10^(-19))/(9.1 xx 10^(-31))[(714)/(2536 xx 3250)])`
`v = 6 xx 10^(5)m//s` or `0.6 xx 10^(6)m//s`