A beam of electrons, each with the same kinetic energy, illuminates a pair of slits separated by a distance of 65 nm. The beam forms bright and dark fringes on a screen located a distance 2 m beyond the two slits. The arrangement is otherwise identical to that used in the optical two-slit interference experiment. The bright fringes are found to be separated by a distance of 0.2 mm. What is the kinetic energy of the electrons in the beam? Planck’s constant is 6.63 × 10−34 J · s. Answer in units of keV.

Ek=142.7keV

Explanation:

First we have to compute the associated wavelength of the electrons by using the formula for the interference condition:

where m is the order of the fringe, lambda is the wavelength of the electrons, d is the distance between the slits and D IS the distance to the screen. By taking m=1, we have that the distance between the first fringes is 0.2mm. Hence, from the middle of the screen we have that y=0.1mm=0.1*10^{-3}m.

By replacing we have:

Now, by using the Broglie's relation we get:

hope this helps!!

i think it's 35 meters

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)