CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2007

  • question_answer
    The resistance of a wire at room temperature \[30{}^\circ C\]is found to be\[10\,\Omega \]. Now to increase the resistance by 10%, the temperature of the wire must be [The temperature coefficient of resistance of the material of the wire is\[0.002/{}^\circ C\]]

    A)  \[36{}^\circ C\]                

    B)         \[83{}^\circ C\]

    C)  \[63{}^\circ C\]                

    D)         \[33{}^\circ C\]

    E)  \[66{}^\circ C\]

    Correct Answer: B

    Solution :

    \[R={{R}_{0}}(1+\alpha t)\] \[\therefore \]  \[{{R}_{0}}(1+30\alpha )=10\,\Omega \] and        \[{{R}_{0}}(1+\alpha )=11\,\Omega \] Therefore,      \[\frac{11}{10}=\frac{1+\alpha t}{1+30\alpha }\] Or           \[11+330\alpha =10+10\alpha t\] Or           \[11+330\times 0.002=10+10\times 0.002t\] Or           \[11.66=0.02t+10\] Or           \[0.02t=1.66\] Or           \[t=83{}^\circ C\]


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