2. Questions Bank
  3. JEE Main & Advanced
  4. Physics
  5. Thermometry, Calorimetry & Thermal Expansion

JEE Main & Advanced Physics Thermometry, Calorimetry & Thermal Expansion Question Bank Self Evaluation Test - Thermal Properties of Matter

  • question_answer
    What is the equivalent thermal conductivity of the rods in figure given below, if the length of each cylinder be \[\ell \] and area of cylinder having thermal conductivities\[{{\operatorname{K}}_{1}}\]and \[{{K}_{3}}\]be A while that of the middle cylinder haying thermal conductivity \[{{K}_{2}}\] be 2A?                                                  

    A) \[\frac{5}{2\left[ \frac{1}{{{K}_{1}}}+\frac{1}{2{{K}_{2}}}+\frac{1}{{{K}_{3}}} \right]}\]

    B) \[\frac{1}{\left[ \frac{1}{{{K}_{1}}}+\frac{1}{2{{K}_{2}}}+\frac{1}{{{K}_{3}}} \right]}\]

    C) \[\frac{2}{5\left[ \frac{1}{{{K}_{1}}}+\frac{1}{2{{K}_{2}}}+\frac{1}{{{K}_{3}}} \right]}\]      

    D) None of these

    Correct Answer: A

    Solution :

    [a] \[\frac{\ell }{{{K}_{1}}A}+\frac{\ell }{2{{K}_{2}}A}+\frac{\ell }{{{K}_{3}}A}=\frac{\ell }{KA}+\frac{\ell }{2KA}+\frac{\ell }{KA}\] \[\frac{5}{2K}=\left( \frac{1}{{{K}_{1}}}+\frac{1}{2{{K}_{2}}}+\frac{1}{{{K}_{3}}} \right)\] \[{{K}_{eq}}=\frac{5}{2\left( \frac{1}{{{K}_{1}}}+\frac{1}{2{{K}_{2}}}+\frac{1}{{{K}_{3}}} \right)}\]


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