question_answer

Directions : In the following question more than one of the answers given may be correct. Select the correct answer and mark it according to the code:

Five equal resistances each of value R are connected in a form shown. The equivalent resistance of the network (1) between the points B and D is\[\frac{R}{2}\] (2) between the points A and C is R (3) between the points B and D is R (4) between the points A and C is \[\frac{R}{2}\]

A)  1, 2 and 3 are correct.

B)  1 and 2 are correct.

C)   2 and 4 are correct.

D)  1 and 3 are correct.

Correct Answer: B

Solution :

                \[\frac{1}{{{R}_{BD}}}=\frac{1}{2R}+\frac{1}{R}+\frac{1}{2R}\] \[\Rightarrow \]               \[{{R}_{BD}}=\frac{R}{2}\] Between A and C circuit becomes equivalent to balanced Wheatstone bridge, so\[{{R}_{AC}}=R\]