question_answer

Seven resistances are connected as shown in the figure. The equivalent resistance between A and B is:

A)  3\[\Omega \]   

B)                         4\[\Omega \]                   

C)  4.5 \[\Omega \]                              

D)         5\[\Omega \]

Correct Answer: B

Solution :

The circuit given in the question can be modified as This is a balanced Wheatstone bridge    Equivalent resistance in upper arm is \[{{R}_{U}}=5+3=8\,\Omega \] Equivalent resistance in lower arm is \[{{R}_{L}}=5+3=8\,\Omega \] Therefore, equivalent resistance of \[{{\text{R}}_{\text{U}}}\]and \[{{\text{R}}_{\text{L}}}\] is \[R=\frac{{{R}_{U}}+{{R}_{L}}}{{{R}_{U}}+{{R}_{L}}}\] \[=\frac{8\times 8}{8+8}=4\,\Omega \]