Uttarakhand PMT Uttarakhand PMT Solved Paper-2005

  • question_answer
    The equivalent resistance \[R{{p}_{Q}}\] between point \[p\] and \[Q\] will be:

    A)  \[8\,\Omega \]

    B)  \[2.4\,\Omega \]

    C)  \[4.5\,\Omega \]

    D)  \[3\,\Omega \]

    Correct Answer: B

    Solution :

     The arms PR, RQ, SP, QS satisfy the condition to from a balanced Wheatstone bridge i.e., \[\left[ \frac{P}{Q}=\frac{R}{S}=\frac{1}{2}=\frac{4}{8} \right]\] Hence, the points R and S are at same potential and resistance RS of\[3\,\Omega \]is not to be taken into consideration. Resistances of upper arm which are connected in series combination their equivalent resistance is given by \[{{R}_{U}}=1+2=3\,\Omega \] Similarly resistances of lower arm which are also connected in series their equivalent resistance is \[{{R}_{L}}=4+8=12\,\Omega \] The resistances\[{{R}_{U}}\] and\[{{R}_{L}}\]are connected in parallel combination then their equivalent resistance between P and Q is \[\frac{1}{{{R}_{PQ}}}=\frac{1}{3}+\frac{1}{12}=\frac{5}{12}\] Or \[{{R}_{PQ}}=\frac{12}{5}=2.4\,\Omega \]


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