NEET-XII-Physics
42: Photoelectric Effect and Wave Particle Duality
- #11Is p - E/c valid for electrons?Ans : From Einstein's mass- energy equation,
E = mc2
`` \Rightarrow E=\frac{{m}_{0}{c}^{2}}{\sqrt{1-{\displaystyle \frac{{v}^{2}}{{c}^{2}}}}}``
Relativistic momentum,
`` p=mv``
`` \Rightarrow p=\frac{{m}_{0}{c}^{2}}{\sqrt{1-{\displaystyle \frac{{v}^{2}}{{c}^{2}}}}}``
Combining the above equations, we get:
`` {E}^{2}={{m}_{0}}^{2}{c}^{4}+{p}^{2}{c}^{2}``
From the above equation, it is clear that for p = E/c to be valid, the rest mass of the body should be zero. As electrons do not have zero rest mass, this equation is not valid for electrons.
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