Using Kirchoff's rules determine the value of unknown resistance R in the circuit so that no current flows through `4 Omega` resistance. Also find the potential difference between A and D.

Explanation

Applying K-Law is classed loop AFEBA.
`9-I xx1-Ixx1-4xx0-6=0`
`implies 9-21-6=0`
`implies 3=2 I`
In loop BEDCB
`6+4xx0-IR-3=0`
`implies IR=3`
`implies R=(3)/(I)=(3)/(3)xx2 implies R= 2 Omega`.
PD between A and D.