CET Karnataka Medical CET - Karnataka Medical Solved Paper-2003

  • question_answer
    A group of N cells whose emf varies directly with the internal resistance as per the equation EN = 1.5 rN are connected as shown in the figure above. The current J in the circuit is:

    A)  5.1 A

    B)  0.51 A

    C)  1.5 A

    D)  0.15 A

    Correct Answer: C

    Solution :

    Given that emf \[{{E}_{N}}={{1.5}_{rN}}\] where \[{{r}_{N}}\] is the internal resistance of nth cell. Total emf  \[E={{E}_{1}}+{{E}_{2}}+{{E}_{3}}+......{{E}_{n}}\]                      \[=1.5[{{r}_{1}}+{{r}_{2}}+{{r}_{3}}+.....+{{r}_{n}}]\] Total internal resistance                  \[r={{r}_{1}}+{{r}_{2}}+{{r}_{3}}+.....+{{r}_{n}}\] \[\therefore \]   current \[i=\frac{{{E}_{total}}}{{{r}_{total}}}\]           \[i=\frac{1.5[{{r}_{1}}+{{r}_{2}}+{{r}_{3}}+.....+{{r}_{n}}]}{[{{r}_{1}}+{{r}_{2}}+{{r}_{3}}+......+{{r}_{n}}]}\] Hence,   \[i=1.5A\]


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