A) \[8\times {{10}^{6}}\]m/s
B) \[8\times {{10}^{5}}\]m/s
C) \[5.9\times {{10}^{6}}\] m/s
D) \[5.9\times {{10}^{5}}\] m/s
Correct Answer: A
Solution :
\[V=200\,\,V,\,\,\frac{e}{m}=1.6\times {{10}^{11}}C/kg\] Kinetic energy of electron\[=eV\] . \[i.e.,\] \[\frac{1}{2}m{{v}^{2}}=eV\] or \[{{v}^{2}}=\frac{2e}{m}V\] or \[v=\sqrt{2\frac{e}{m}V}\] \[=\sqrt{2\times 1.6\,\times {{10}^{11}}\times 200}\] \[=8\times {{10}^{6}}m/s\]
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