Matter Waves: The electrons in a beam are moving at 18 m/s. (melectron = 9.11 × 10-31 kg, h = 6.626 × 10-34 J ? s) (a) What is its de Broglie wavelength these electrons?(b) If the electron beam falls normally on a diffraction grating, what would have to be the spacing between slits in the grating to give a first-order maximum at an angle of 30° with the normal to the grating?

Fill in the blank(s) with the appropriate word(s).


(a) 40 ?m (b) 81 ?m

Physics & Space Science

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