A stream of electrons from a heated filament was passed between two charged plates kept at a potential difference V esu. If c and m are charge and mass of an electron repectively, then the value of `h//lambda` (where `lambda` is wavelength associated with electron wave) is given by :

Options

A. `me V`
B. `2 me V`
C. `sqrt(me V)`
D. `sqrt(2 meV)`

Answer

D

Explanation

`lamda = (h)/(p) or (h)/(lamda) = p = mv`
`KE = (1)/(2)mv^(2)` so that `v = sqrt((2KE)/(m)) " But " KE = eV`
`:. v = sqrt((2eV)/(m)) :. (h)/(lamda) = mv = m sqrt((2eV)/(m)) = sqrt(2meV)`