2. Solved Papers
  3. MGIMS WARDHA

MGIMS WARDHA MGIMS WARDHA Solved Paper-2004

  • question_answer
    A steel scale measures the length of a copper wire as 80.0 cm, when both are at 20°C, the calibration temperature for the scale. What would the scale read for the length of the wire when both are at 40°C?                    Given: \[\alpha \] for steel \[=11\times {{10}^{-6}}\] per °C and a for \[Cu=17\times {{10}^{-6}}\]per °C:

    A) 80.0096 cm                         

    B) 80.0272 cm     

    C) 1 cm                                      

    D) 25.2 cm        

    Correct Answer: A

    Solution :

    Using the relation \[{{l}_{t}}={{l}_{0}}(1+\alpha t)\] \[=1\times [1+11\times {{10}^{-6}}\times ({{40}^{o}}-{{20}^{o}})]\] \[=1.00022\,cm\] Now, length of copper rod at\[40{}^\circ C\] \[l_{t}^{'}=l_{0}^{'}(1+\alpha 't)\] \[=80\text{ }[1+17\times {{10}^{-6}}(40{}^\circ -20{}^\circ )]\] \[=80.0272\text{ }cm\] Now, number of cms observed on the scale \[=\frac{80.0272}{1.00022}=80.0096\]


You need to login to perform this action.
You will be redirected in 3 sec spinner