what should be the velocity of an electron so that its momentum becomes equal to that of a photon of wavelength `5200 Å`

Explanation

According to de Broglie equation, `lambda =(h)/(m upsilon) `
Momentum of electron , ` m upsilon = (h)/(lambda)=((6.626 xx 10^(-34)kg m ^(2) s^(-1)))/((5200 xx 10^(-10)m))=1.274 xx 10^(-27) kg ms^(-1) ...(i)`
The momentum of electron can also be calculated as `= m upsilon = (9.1 xx 10^(-31)kg) xx upsilon " " ...(ii)`
Comparing (i) and (ii)
`(9.1 xx 10^(-31)kg)xx upsilon = (1.274 xx 10^(-27) kg ms^(-1))`
` :. " " upsilon= ((1.274 xx 10^(-27) kg ms^(-1)))/((9.1 xx 10^(-31) kg))= 1.4 xx 10^(3) m s^(-1)`