An x-ray diffraction experiment using 16 -keV x-rays is repeated using electrons instead of \(x\) -rays. What should the kinetic energy of the electrons be in order to produce the same diffraction pattern as the x-rays (using the same crystal)?

Short Answer

Expert verified
Answer: To find the kinetic energy of electrons required to produce the same diffraction pattern as the x-rays, follow these steps: 1. Calculate the x-ray wavelength using the energy-wavelength relationship: \(\lambda_x = \frac{hc}{E_x}\) 2. Find the de Broglie wavelength of electrons with the same wavelength as the x-rays (\(\lambda_e = \lambda_x\)). 3. Determine the electron momentum using the de Broglie wavelength formula: \(p_e = \frac{h}{\lambda_e}\) 4. Relate electron momentum to its kinetic energy: \(K_e = \frac{p_e^2}{2m_e}\) 5. Calculate the kinetic energy of electrons in Joules and convert it to electron volts (eV): \(K_e (eV) = \frac{K_e (J)}{1.6 \times 10^{-19}\text{J/eV}}\) By following these steps and plugging in the given values and known constants, you can find the kinetic energy of electrons required to produce the same diffraction pattern as 16-keV x-rays using the same crystal.

Step by step solution

01

Calculate the x-ray wavelength

First, convert the x-ray energy to the wavelength. We are given the x-ray energy (\(E_x\)) as 16 keV, which needs to be converted to Joules (1 eV = 1.6 x 10^{-19} J). The relationship between an x-ray's energy and its wavelength (\(\lambda_x\)) is: \(\lambda_x = \frac{hc}{E_x}\) where \(h\) is the Planck's constant (\(6.626 \times 10^{-34}\) Js), and \(c\) is the speed of light (\(3 \times 10^8\) m/s).
02

Calculate the de Broglie wavelength of electrons

Now that we know the x-ray wavelength, we want electrons with the same wavelength. The de Broglie wavelength formula relates the wavelength of particles to its momentum, which is: \(\lambda_e = \frac{h}{p_e}\) where \(\lambda_e\) is the electron wavelength, and \(p_e\) is electron momentum. For the electrons to have the same wavelength as the x-rays, we need \(\lambda_e = \lambda_x\).
03

Find the electron momentum

Since we now know the electron wavelength, we can find the electron momentum. From the de Broglie wavelength formula: \(p_e = \frac{h}{\lambda_e}\) Now, substitute \(\lambda_x\) for \(\lambda_e\): \(p_e = \frac{h}{\lambda_x}\)
04

Relate electron momentum to its kinetic energy

We want to find the kinetic energy (\(K_e\)) of the electrons. The relationship between the electron momentum and kinetic energy is given by: \(K_e = \frac{p_e^2}{2m_e}\) where \(m_e\) is the mass of the electron (\(9.11 \times 10^{-31}\) kg).
05

Calculate the kinetic energy of electrons

Now, we can substitute the expression for electron momentum from Step 3 into the kinetic energy equation and solve for the kinetic energy of electrons. \(K_e = \frac{(h/\lambda_x)^2}{2m_e}\) We've previously calculated \(\lambda_x\) in Step 1, \(h\) and \(m_e\) are known constants, so we can now find \(K_e\). Once you have found the kinetic energy of electrons (\(K_e\)) in Joules, convert it to electron volts (eV) by dividing the value by \(1.6 \times 10^{-19}\). This will give you the kinetic energy of electrons required to produce the same diffraction pattern as the 16-keV x-rays using the same crystal.

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