Question

If the momentum of an electron is changed by `Delta p` , then the de - Broglie wavelength associated with it changes by `0.50 %`. The initial momentum of the electron will be
A. `(Delta p)/(200)`
B. `(Delta p)/(199)`
C. `199 Delta p`
D. `400 Delta p`

Answer 1

Correct Answer - C
`lambda = (h)/(p) rArr lambda - (0.5)/(100) lambda = (h)/( p + Delta p)`
`rArr (199 lambda)/(200) = (h)/(p + Delta p) = (199)/(200) (h)/(p)`
`rArr p + Delta p = (2000)/(199) p rArr p = 199 Delta p`