Abeam of electrons, each with the same kinetic energy, illuminates a pair of slits separated by a distance of 52 nm. the beam forms bright and dark fringes on a screen located a distance 1.8 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 1 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.

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

answer///isobars;