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5. A X-ray photon of
collides with a stationary free electron, the wavelength of the scattered
-ray photon increases to
. Then, the velocity of the electron becomes
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5. A X-ray photon of
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Ask by Riley Lewis. in Egypt
Mar 28,2025
Upstudy AI Solution
Tutor-Verified Answer
Answer
The electron’s velocity after the collision is
.
Solution
We first note that when the
-ray photon collides with a free electron and its wavelength increases, the lost photon energy is transferred to the electron as kinetic energy. We can find the kinetic energy
of the electron from the energy difference of the photon before and after scattering.
Step 1. Write the photon energies
The energy of a photon is given by
where
-
is Planck’s constant, -
is the speed of light, -
is the wavelength.
A commonly used value is
. The initial and final energies are then
Step 2. Compute the energies
Calculate the initial energy:
Calculate the final energy:
Step 3. Find the energy transferred to the electron
The kinetic energy of the electron is the energy difference:
Step 4. Convert the kinetic energy to Joules
We use the conversion factor
:
Step 5. Determine the electron’s velocity
The kinetic energy is related to the velocity
of the electron by
where
is the electron mass. Solving for
, we have
Substitute the numerical values:
Perform the calculation:
Thus, the velocity of the electron after collision is
This corresponds to the option
.
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Beyond the Answer
When an X-ray photon collides with a stationary electron, the interaction can be analyzed using the Compton scattering formula. In this case, the change in wavelength due to scattering indicates that the photon transferred some of its energy to the electron. This results in the electron acquiring kinetic energy, which can be calculated to find its velocity. This phenomenon shows the dual nature of light, acting as both a wave and a particle!
If you’re diving into photon-electron interactions like the one described, a common mistake is neglecting to consider conservation of momentum alongside energy. Both energy and momentum must be conserved in these collisions. Always check your equations and ensure that you account for both transverse and longitudinal momentum directions to avoid hefty errors in your calculations!