Two resistances $r_1$ and $r_2$ $(r_1 < r_2)$ are joined in parallel. The equivalent resistance $R$ is such that

The equivalent resistance between $A$ and $B$ is $6 \Omega$. The value of $R_1$ is (in $Omega$)

Resistance $n$,each of $r \ \Omega$,when connected in parallel give an equivalent resistance of $R \ \Omega$. If these resistances were connected in series,the combination would have a resistance in $\Omega$,equal to

Two wires $A$ and $B$ are made of the same material and have the same mass. The radius of wire $A$ is twice the radius of wire $B$. If wires $A$ and $B$ are connected in parallel,the equivalent resistance will be:

Two $10\,\Omega$ resistors are first connected in series and then in parallel. What is the ratio of the equivalent resistance in both cases?

In the given circuit,find the value of $V$. (in $V$)