Chhattisgarh PMT Chhattisgarh PMT Solved Paper-2009

  • question_answer 160W-60V lamp is connected at 60 V DC Supply. The number of electrons passing trough the lamp in 1 min is

    A) \[{{10}^{19}}\]                                  

    B) \[{{10}^{21}}\]

    C) \[1.6\times {{10}^{19}}\]                             

    D) \[1.4\times {{10}^{20}}\] (The charge of electron \[1.6\times {{10}^{-19}}C)\]

    Correct Answer: B

    Solution :

    Power, \[P=\frac{{{V}^{2}}}{R}\] \[R=\frac{{{V}^{2}}}{P}\] \[=\frac{{{(60)}^{2}}}{160}=22.5\Omega \] 'view. according to Ohm's law                 \[V=IR\] \[\therefore \]  \[I=\frac{60}{22.5}\] \[\Rightarrow \]               \[I=2.6A\] Here,     \[t=60s\] As           \[I=\frac{ne}{t}\] \[\Rightarrow \]               \[n=\frac{I\times t}{e}\]                 \[=\frac{2.6\times 60}{1.6\times {{10}^{-19}}}\]                 \[\approx {{10}^{21}}\]


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