Question

The equivalent resistance between the points a and b of the electrical network shown in the figure is

• A. $6r$
• B. $4r$
• C. $2r$
• D. $r$

Answer 1

The correct option is D $r$

The given circuit is a balanced wheat stone bridge, thus no current flows through the resistors connected in centre.

Equivalent resistance between a and b $R_{eq}=(r+r)\parallel (r+r)$

$\therefore$ $R_{eq}=2r\parallel 2r$

$⟹$ $R_{eq}=\frac{2r\times 2r}{2r+2r}=r$