A wire of $15 \mathrm{\Omega }$ resistance is gradually stretched to double its original length. It is then cut into two equal parts. These parts are then connected in parallel across a $3.0$ volt battery. Find the current drawn from the battery.

The reading of the (ideal) ammeter, in the circuit shown here, equals:

(i) $I$ when the key $K_7$ is closed but the key $K_2$ is open.

(ii) $\frac{1}{2}$ when both keys $K_1$ and $K_2$ are closed.

Find the expression for the resistance of $X$ in terms of the resistances of $R$ and $S$.

Five resistors are connected as shown in Fig. Find the equivalent resistance between points $B$ and $C$.

If the reading of the ammeter $A_1$ in Fig. is $2.4 \mathrm{A}$, what will the ammeters $A_2$ and $A_3$ read? Neglect the resistances of the ammeters.

The resistance of the rheostat shown in Fig. is $30 \mathrm{\Omega }$. Neglecting the meter resistance, find the minimum and maximum current through the ammeter as the resistance of the rheostat is varied.