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1. A 0.828-nm photon collides with a stationary electron. After the collision, the electron moves forward and the photon recoils backwards.
a) Find the momentum of the electron.

b) Find the kinetic energy of the electron.

Respuesta :

Erythrosin17
a) Find the momentum of the electron.

The momentum would be as follows:
p = E / c 
p= (h(c) / (wavelength)) / c 
p = h / wavelength
p = 6.626x10^-34 J s / 0.828x10^-9 m 
p = 8.00 x 10^-25 kg m/s 

b) Find the kinetic energy of the electron.

Assuming this is a head-on collision, then cosine of the angle would be -1. 
wavelength (after) - wavelength (before) = 2(h / m(e) c) 
wavelength (after) = 2(h/m(e) c) + wavelength (before) 
wavelength (after) = 0.00485 nm + 0.828 nm 
wavelength (after) = 0.83385 nm 

E = h(c)/wavelength 
E(before) = h c / 0.828x10^-9 = 2.4x10^-16 J
E(after) = h c / 0.83385 x10^-9 = 2.38 x10^-16 J 
Total change in E = 2.4x10^-16 J - 2.38 x10^-16 J 
Total change in E = 3.16x10^-17 J

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