Find the initial momentum of electron if the momentum of electron is changed by `p_(m)` and the De Brogile wavelength associated with it changed by `0.50%`

Answer

`19.90`

Explanation

Let p be initial momentum of electron, `p. = p + p_(e)`
`therefore lambda. = lambda - 0.5/100 lambda = (1- 0.5/100) lambda`
`therefore (lambda.)/lambda = p/p^(.)`
`therefore (1- 0.5/100) = p/(p+p)`
`therefore 9.5p + 9.5p_(m) = 100 p`
`therefore 0.5 p= 99.5 p_(m)`
`therefore p = 199p_(m)`