An x-ray photon is scattered from a free electron (mass m) at rest. The wavelength of the scattered photon is λ′, and the final speed of the struck electron is v.

a. What was the initial wavelength λ of the photon? Express your answer in terms of λ′, v, m, and the appropriate constants. For the wavelength of the scattered photon λ′ use the notation λf. (Hint: Use the relativistic expression for the electron kinetic energy.)
b. Through what angle ϕ is the photon scattered? Express your answer in terms of λ′, λ, m, and the appropriate constants. For the wavelength of the scattered photon λ′ use the notation λf.
c. Evaluate your result in part A for a wavelength of 5.50×10−3nm for the scattered photon and a final electron speed of 1.80×10^8m/s.
d. Evaluate your result in part B for a wavelength of 5.50×10−3nm for the scattered photon and a final electron speed of v. Give ϕ in degrees.

a and c

c is 100% but i am confused in a

nah.   i'm just sleepy.

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.

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.