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

  • question_answer
    A 100 W bulb B1, and two 60-W bulbs B2 and B3, are connected to a 250 V source, as shown in the figure. Now W1, W2 and W3 are the output powers of the bulbs B1, B2 and B3, respectively. Then                       [IIT-JEE (Screening) 2002]

    A)            \[{{W}_{1}}>{{W}_{2}}={{W}_{3}}\]                               

    B)            \[{{W}_{1}}>{{W}_{2}}>{{W}_{3}}\]

    C)            \[{{W}_{1}}<{{W}_{2}}={{W}_{3}}\]                               

    D)            \[{{W}_{1}}<{{W}_{2}}<{{W}_{3}}\]

    Correct Answer: D

    Solution :

                       \[P=\frac{{{V}^{2}}}{R}\] so \[R=\frac{{{V}^{2}}}{P}\] Þ \[{{R}_{1}}=\frac{{{V}^{2}}}{100}\] and \[{{R}_{2}}={{R}_{3}}=\frac{{{V}^{2}}}{60}\] Now \[{{W}_{1}}=\frac{{{(250)}^{2}}}{{{({{R}_{1}}+{{R}_{2}})}^{2}}}.{{R}_{1}}\], \[{{W}_{2}}=\frac{{{(250)}^{2}}}{{{({{R}_{1}}+{{R}_{2}})}^{2}}}.{{R}_{2}}\] and \[{{W}_{3}}=\frac{{{(250)}^{2}}}{{{R}_{3}}}\] \[{{W}_{1}}:{{W}_{2}}:{{W}_{3}}=15:25:64\] or  \[{{W}_{1}}<{{W}_{2}}<{{W}_{3}}\]


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