Thank you for reporting, we will resolve it shortly
Q.
Find the value of $R$ for which no current will flow through $5\, V$ battery.
Current Electricity
Solution:
If no current flows through $5\, V$ battery, then potential difference across $f$ and e is $5 \,V$. So potential difference across $d$ and $c$ is also $5 \,V$.
$i=\frac{10}{R+1}$
$i R=5 \Rightarrow \frac{10}{(R+1)} R=5 $
$\Rightarrow R=1 \,\Omega$