NEET Physics Current Electricity, Charging & Discharging Of Capacitors / वर्तमान बिजली, चार्ज और कैपेसिटर का निर NEET PYQ-Current Electricity Charging Capacitors

  • question_answer
    The internal resistance of a cell of emf 2 V is \[0.1\,\,\Omega \]. It is connected to a resistance of \[3.9\,\,\Omega \,\]. The voltage across the cell will be:                                                                                          [AIPMT 1999]

    A)  0.5 V   

    B)       1.9 V

    C)  1.95 V

    D)       2 V

    Correct Answer: C

    Solution :

    [c] Key Idea: Terminal voltage across the cell decreases due to voltage drop across internal resistance.
                The current flowing in the circuit is
                            \[i=\frac{E}{R+r}\]
                Given,   \[E=2\text{ }V,\text{ }R=3.9\,\Omega ,\]
                            \[r=0.1\,\Omega \]
                So,       \[i=\frac{2}{3.9+0.1}=\frac{2}{4.0}=0.5\,A\]
                The voltage drop across internal resistance,
                            \[V'=ir=0.5\times 0.1\]
                            \[1=0.05\text{ }V\]
                Thus, terminal voltage across cell is,
                            \[V=E-ir=E-V'\]
                            \[=2-0.05=1.95\,V\]            


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