JEE Main & Advanced Physics Current Electricity, Charging & Discharging Of Capacitors / वर्तमान बिजली, चार्ज और कैपेसिटर का निर Question Bank Critical Thinking

  • question_answer
      A torch bulb rated as 4.5 W, 1.5 V is connected as shown in the figure. The e.m.f. of the cell needed to make the bulb glow at full intensity is                                            [MP PMT 1999]           

    A)            4.5 V

    B)            1.5 V

    C)            2.67 V

    D)            13.5 V

    Correct Answer: D

    Solution :

                       Current in the bulb \[=\frac{P}{V}=\frac{4.5}{1.5}=3A\] Current in 1 W resistance \[=\frac{1.5}{1}=1.5A\] Hence total current from the cell \[i=3+1.5=4.5A\] By using \[E=V+ir\]Þ \[E=1.5+4.5\times (2.67)=13.5V\]


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