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NEET Sample Paper NEET Sample Test Paper-81

  • question_answer
    A uniform wire when connected directly across a 200 V line produces heat H per second. If the wire is divided into n parts and all parts are connected in parallel across a 200 V line. The heat produced per second will be

    A)   H                               

    B)  nH

    C)  \[{{n}^{2}}H\]                      

    D)  \[\frac{H}{{{n}^{2}}}\]

    Correct Answer: C

    Solution :

    As, \[H=\frac{{{V}^{2}}}{R}\]                        (for 1 s) Resistance of each part \[=\,\,\frac{R}{n}\] When all parts are connected in parallel, net resistance \[R'=\frac{R}{{{n}^{2}}}\] So, heat produced \[H'=\frac{{{V}^{2}}}{R'}\] \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\frac{H'}{H}=\frac{R}{R'}=\frac{R}{\left( \frac{R}{{{n}^{2}}} \right)}={{n}^{2}}\] \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,H'={{n}^{2}}H\]


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