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

`lambda_(0) = 3250 Å`
`lambda = 2536 Å`
`(1)/(2) mv^(2) = hc[ (1)/(lambda) - (1)/(lambda_(0))]`
`v = sqrt((2hc)/(m) [(1)/(lambda) - (1)/(lambda_(0))]`
`= sqrt(( 2 xx 12400 xx 1.6 xx 10^(-19))/(9.1 xx 10^(-31)) [(714)/(2536 xx 3250)]`
` = 0.6 xx 10^(6) m//s = 6 xx 10^(5) m//s`