12th Class Physics Current Electricity, Charging & Discharging Of Capacitors / वर्तमान बिजली, चार्ज और कैपेसिटर का निर Question Bank MCQ - Current Electricity

  • question_answer
    The resistance of a heating element is \[99\,\Omega \]at room temperature. What is the temperature of the element, if the resistance is found to be \[116\,\Omega \]?                   (Temperature coefficient of the material of the resistor is \[1.7\times {{10}^{-4}}{}^\circ {{C}^{-1}}\])

    A) \[999.9{}^\circ C\]                   

    B) \[1005.3{}^\circ C\]

    C) \[1020.2{}^\circ C\]                  

    D) \[1037.1{}^\circ C\]

    Correct Answer: D

    Solution :

    (d) \[1037.1{}^\circ C\] Here,    \[{{\text{R}}_{0}}=99\,\Omega ,{{T}_{0}}=27{}^\circ C\]             \[{{\text{R}}_{T}}=116\,\Omega ;\,\alpha =1.7\times {{10}^{-4}}\,{}^\circ {{C}^{-1}}\] \[\therefore {{R}_{T}}={{R}_{0}}[1+\alpha (T-{{T}_{0}})]\] \[\therefore \frac{{{R}_{T}}}{{{R}_{0}}}-1=\alpha (T-{{T}_{0}})\] \[\Rightarrow \frac{116}{99}-1=\alpha \,(T-{{T}_{0}})\] \[T={{T}_{0}}=\frac{1}{\alpha }\left[ \frac{116-99}{99} \right]=\frac{17}{99\alpha }=\frac{1}{1.7\times {{10}^{-4}}}\times \frac{17}{99}\] \[\therefore T-{{T}_{0}}=\frac{{{10}^{5}}}{99}=1010.10{}^\circ C\] \[\Rightarrow T=1010.1+{{T}_{0}}=1010.1+27=1037.1{}^\circ C\]


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