Out of the following options in which case in the velocity of electron greater than `1.5xx10^(6)`m//s.
{hc=1240 eV-nm}

Options

A. An electron moving in the first Bhor radius of hydrogen atom
B. The electron which is accelerated from rest positiove by an potenital of `3.4 eV`.
C. The electron having deBroglie wavelenght of `2pixx0.529Å`.
D. The electron with maximum kinetic energy emitted from a mental whose threshlod wavelenght wavelenght is 400
nm and is subjected to eleectromagnetic radiations having wavelenght 124nm.

Answer

A, C, D

Explanation

(A) `V_(1)=2.188xx10^(6)xx(Z)/(n)m//sec.`
`V_(1)(ngt1)=2.188xx10^(6)m//sec.`
(B) `3.4xx1.6xx10^(-19)=(1)/(2)xx9.1xx10^(-31)xxV^(2)`
`V=(2xx3.4xx1.6)/(9.1)=10^(+12)`
`=1.09xx10^(6)m//sec`
(c) `2pir=nlambda`
`2pi(0.529xxn^(2)/Z)-nxx2pixx0.529`
`n=1`
`V_(1)=2.18 xx10^(6) m//sec`
(D) energy of electron `= 6.9 eVrArr(1)/(2)mv^(2)`
`v=1.55xx10^(6)m//sec`]