1.

An electron has kinetic energy `2.8 xx 10^-23 J` de-Broglie wavelength will be nearly. `(m_e = 9.1 xx 10^-31 kg)`.A. `9.28 xx 10^-4 m`B. `9.28 xx 10^-7 m`C. `9.28 xx 10^-8 m`D. `9.28 xx 10^-10 m`

Answer» Correct Answer - C
( c) Formule for de-Broglie wavelength is
`lamda = (h)/(p)` or` lamda =(h)/(mv) rArr eV = (1)/(2) mv^2` or `v = sqrt((2 eV)/(m))`
`lamda = (h)/(sqrt(2 meV)) = (6.62 xx 10^-34)/(sqrt(2 xx 9.1 xx 10^-31 xx 2.8 xx 10^-23))`
`lamda = 9.28 xx 10^-8 "meter"`.


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