What voltage must be applied to an elecron microscope to produce electrons of wavelength `0.4 overset @A`?

Explanation

Voltage =V=?
`lamda= 0.4 Å= 0.04 xx 10^(-10)m`
`=4 xx 10^(-11)m`
`lamda= (h)/(sqrt(2meV))`
On squaring, `lamda^(2)= (h^(2))/(2meV)`
`V= (h^(2))/(2me lamda^(2))`
`=((6.62 xx 10^(-34))^(2))/(2xx 9.1 xx 10^(-31) xx 1.6 xx 10^(-19) xx (4 xx 10^(-11))^(2))`
`=0.09406 xx 10^(4)`
V= 940.6 volt.