InterviewSolution
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InterviewSolution
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Crystal diffraction experiments can be performed using X-rays, or electrons accelerated through appropriate voltage. Which probe has greter energy? An X-ray photon or the electron? (For quantiative comparision, take the wavelength of the probe equal to `1Å`, which is of the order of interatomic spacing in the lattice), `m_(e)=9.11xx10^(-31)kg`. |
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Answer» For producing X-rays, kinetic energy of electron is involved. K.E. of electron, `E=1/2mv^(2) or mv=sqrt(2Em) and lambda=h/(mv)=h/(sqrt(2Em))` `:. E=(h^(2))/(2lambda^(2)m)=((6.63xx10^(-34))^(2))/(2xx10^(-20)xx9.11xx10^(-31))J = ((6.63xx10^(-34))^(2))/(2xx9.11xx10^(-51)xx1.6xx10^(-19)) eV=150.6 eV` For photons, `lambda=1Å=10^(-10)m` `:.` Energy of photon, `E=hv=(hc)/lambda=(6.63xx10^(-34)xx3xx10^(8))/(10^(-10)xx1.6xx10^(-19)) eV=12.4xx10^(3) eV` Thus for the same wavelength, a photon has much greater kinetic energy than an electron. |
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