With what speed do the electrons strike the screen? hint: the kinetic energy of an electron which has been accelerated through a potential difference of 1 v has a kinetic energy equal to 1 ev.

3.5 X 10^11 m/s

Explanation:

1 eV is the amount of energy associated with moving one electron through a potential difference of 1 volt.

1 eV = 1.6 x 10-19 J

Mass of electron=9.11 × 10-31

K.E =MV^2/2

V=√(2K.E/M)

V=3.5 X 10^11

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.)

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.