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11.Dual Nature of Radiation and matter
medium
An electron with (rest mass $m_{0}$ ) moves with a speed of $0.8 c$. Its mass when it moves with this speed is
A
$m_0$
B
$m_0/6$
C
$5m_0/3$
D
$3m_0/5$
(AIPMT-1991)
Solution
speed $ = {\rm{0}}{\rm{.8c}}$
${\rm{m}} = \frac{{{{\rm{m}}_{\rm{0}}}}}{{\sqrt {{\rm{1 – }}\frac{{{{\rm{v}}^{\rm{2}}}}}{{{c^2}}}} }} = \frac{{{n_0}}}{{\sqrt {1 – \frac{{{{0.64}^2}}}{{{c^2}}}} }}\,\,\,;$
$m = \frac{{{m_0}}}{{0.6}} = \frac{5}{3}{m_0}$
Standard 12
Physics