A) 3.31 cm
B) 4.31 cm
C) 1.31cm
D) 2.35 cm
Correct Answer: D
Solution :
When electron moves at right angles in a magnetic field , then Centripetal force = Force due to magnetic field \[\frac{m{{v}^{2}}}{r}=ev\,\,B\sin \theta \] \[\Rightarrow \] \[r=\frac{m}{e}\,.\,\,\frac{v}{B}\,.\,\,\frac{1}{\sin \theta }\] Given, \[\frac{e}{m}=1.7\times {{10}^{11}}C/kg\], \[v=6\times {{10}^{7}}m/s\], \[B=1.5\times {{10}^{-2}}T,\,\,\,\theta ={{90}^{o}}\] \[\Rightarrow \] \[r=\frac{1}{1.7\times {{10}^{11}}}\times \frac{6\times {{10}^{7}}}{1.5\times {{10}^{-2}}}\] \[=2.35\times {{10}^{-2}}m\] \[\Rightarrow \] \[r=2.35\,\,cm\]You need to login to perform this action.
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