Diffrraction of electron experiment to be observable

[desmond iking]

in my textbook , it states that for the diffrraction of electron experiment to be observable, the De Broglie's wavelength of the particles is of the same order as the interatomic spacing... i have a doubt here... what is the meaning of same order here?

 

[Simon Bridge]

"same order" usually means the "order of magnitude" - it basically means that they should have the same power of ten when placed in scientific notation. It can refer to the order of the Taylor series approximation you may learn about later.

In this context it is a bit hand-wavey but serves as a filler until you learn the real theory.
Read: the dB wavelength has to be in the same ballpark as the slit width.

You can actually check this from the usual equation ... write the slitwidth as a function of the wavelength and the angular fringe spacing.
What is the smallest angle that can be comfortably measured - about 1deg? 2-5deg? plug it in and see what you get for the slit width. Compare with the incoming wavelength.