Question

When some potential difference is maintained between $A$ and $B$, current i enters the network at $A$ and leaves at $B$ as shown in the figure. Then
(1) The equivalent resistance between $A$ and $B$ is $8\Omega$.
(2) $C$ and $D$ are at the same potential
(3) Current $\frac{3i}{5}$ flows from $D$ to $C$
(4) No current flows between $C$ and $D$

• 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

Answer 1

Answer: (A)

The equivalent resistance between points $A$ and $B$ is

$R_{eq}=\frac{20\times 5}{20+5}+\frac{5\times 20}{5+20}$
$R_{eq}=8\Omega$
$C$ and $D$ are joined, they must be at the same potential.

$V_A-V_C=V_A-V_D$
$20i_1=5\left(i-i_1\right)$
$i_1=\frac{i}{5}$
Current flowing from $D$ to $C$ is
$i-2i_1=i-\frac{2i}{5}=\frac{3i}{5}$