Question

The resistance of the following circuit figure between $A$ and $B$ is

• A. $(3/2)\Omega$
• B. $2\Omega$
• C. $4\Omega$
• D. $8\Omega$

Answer 1

Answer: (A)

Since resistance connected in arms $CE,ED,CF$ and $FD$ will form a balanced Wheatstone bridge, therefore, the resistance of arm EF becomes ineffective.
Now resistance of arm CED or $CFD=2+2=4\Omega$.
Effective resistance of these two parallel arm
$=\frac{4\times 4}{4+4}=2\Omega$
Now resistance of arm $ACDB=2+2+2=6\Omega$, is in parallel with resistance arm $AB=2\Omega$.
Thus, effective resistance between $A$ and $B=\frac{6\times 2}{6+2}=\frac{3}{2}\Omega$