By which of the following single load resistance should the load bridge be replaced so that the power to the load remains unchanged (in $\Omega$)? (Given $r = 3 \ \Omega$ for each resistor in the bridge)

The ammeter reading in the circuit below is .............. $A$.

Two resistances are joined in parallel whose resultant is $6/8 \, \Omega$. One of the resistance wires is broken and the effective resistance becomes $2 \, \Omega$. Then the resistance in ohm of the wire that got broken was:

For the mixed connection shown in the figure,derive the equation for the equivalent resistance.

$A$ wire of resistance $20 \Omega$ is divided into $10$ equal parts. $A$ combination of two parts are connected in parallel and so on. Now,the resulting pairs of parallel combinations are connected in series. The equivalent resistance of the final combination is . . . . . . $\Omega$.

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