Chhattisgarh PMT Chhattisgarh PMT Solved Paper-2006

  • question_answer
    A proton, a deuteron and an a-particle having the same momentum, enters a region of uniform electric field between the parallel plates of a capacitor. If the electric field is perpendicular to the initial direction of the particles. Then, the ratio of deviations of these particles

    A)  1:2:8                                    

    B)  1:2:4

    C)  1:2:2                                    

    D)  1:1:2

    Correct Answer: A

    Solution :

    Force acting on charge particle in normal direction of motion. \[F=Eq\] Acceleration   \[a=\frac{F}{m}=\frac{Eq}{m}\] If particle travels a distance d in lime t, then                 \[t=\frac{d}{v}\] Motion in normal direction                 \[y=\frac{1}{2}a{{t}^{2}}\]                 \[y=\frac{1}{2}\times \frac{Eq}{m}\times \frac{{{d}^{2}}}{{{v}^{2}}}\] But        \[p=mv\] \[\therefore \]  \[y=\frac{Eq{{d}^{2}}.m}{2{{p}^{2}}}\] \[\therefore \]  \[y\propto \frac{qm}{{{p}^{2}}}\] \[\therefore \]  \[{{y}_{p}}:{{y}_{d}}:{{y}_{\alpha }}=\frac{{{q}_{p}}{{m}_{p}}}{p_{p}^{2}}=\frac{{{q}_{d}}{{m}_{d}}}{p_{d}^{2}}=\frac{{{q}_{\alpha }}{{m}_{\alpha }}}{p_{\alpha }^{2}}\] Given,      \[{{p}_{p}}={{p}_{d}}={{p}_{\alpha }}\] \[{{q}_{p}}=e,\]                                \[{{q}_{d}}=e,\]                                \[{{q}_{\alpha }}=2e\] \[{{m}_{p}}=m,\]             \[{{m}_{d}}=2m,\]           \[{{m}_{\alpha }}=4m\] \[\therefore \] \[{{y}_{p}}:{{y}_{d}}:{{y}_{\alpha }}=e\times m:e\times 2m:2e\times 4m\]                 \[=1:2:8\]


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