Rest mass energy of an electron is 0.51 | vedclass

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Question

(b) Given $m_0c^2$ $= 0.51 \  MeV$ and $v = 0.8\  c$

$K.E$. of the electron = $mc^2$-$m_0c^2$

But $m = \frac{{{m_0}}}{{\sqrt {1 - \fra

Vedclass · Accepted Answer

$0.34$

Vedclass · Answer

(b) Given $m_0c^2$ $= 0.51 \  MeV$ and $v = 0.8\  c$

$K.E$. of the electron = $mc^2$-$m_0c^2$

But $m = \frac{{{m_0}}}{{\sqrt {1 - \frac{{{v^2}}}{{{c^2}}}} }} = \frac{{{m_0}}}{{\sqrt {1 - {{\left( {\frac{{0.8\,c}}{c}} ight)}^2}} }} = \frac{{{m_0}}}{{\sqrt {0.36} }} = \frac{{{m_0}}}{{0.6}}$

Now, $m{c^2} = \frac{{0.51}}{{0.6}}$ $MeV = 0.85\  MeV $

$	herefore K.E. = (0.85 -0.51)\ MeV = 0.34\  MeV.$

Rest mass energy of an electron is $0.51\ MeV.$ If this electron is moving with a velocity $0.8\ c$ (where $c$ is velocity of light in vacuum), then kinetic energy of the electron should be. ........... $MeV$

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