4. The wavelength of the threshold is 550nm. 4/1 - Find the output work in) and eV.
4/2 - Find Ek nas electrons detach under the action of light A = 440nm.
4/3 - Find the max velocity of the electrons.​

are their multiple choices ?

explanation:

because growing process had stoped after 4-5 year

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.

inverse v=i*r

nice nice