Question

Choose the correct option/options:

When some potential difference is maintained between A and B, current / enters the network at A and leaves at B:

• A. the equivalent resistance between A and B is $8\Omega$
• B. C and D are at the same potential
• C. no current flows between C and D
• D. current (3/5) flows from D to C

Answer 1

Answer: (A), (B), (D)

The correct options are
A C and D are at the same potential
B the equivalent resistance between A and B is $8\Omega$
D current (3/5) flows from D to C

As C and D are connected by a wire they are at same potential.
So the circuit can be replaced by that given in figure.
Between AC $[R_{eq}=(20\times 5)/20+5]$ ohm
Between CB $[R_{eq}=(20\times 5)/20+5]$ ohm
So between AB $[R_{eq}=4+4]$ ohm
$[R_{eq}=8]$ ohm
By symmetry the amount of current passing through 20 ohm resistance between AC will be equal to the current passing through the 20 ohm resistance between CB
$[20\times I_1=5\times (I-I_1\left)\right]$
$[I_1=I/5]$
Therefore, $[I-2\times I_1=(3/5\left)I\right]$