The equivalent resistance between points $A$ and $B$ in the given network is ............ $\Omega$.

$(a)$ Three resistors $2 \; \Omega$,$4 \; \Omega$,and $5 \; \Omega$ are combined in parallel. What is the total resistance of the combination?
$(b)$ If the combination is connected to a battery of $emf \; 20 \; V$ and negligible internal resistance,determine the current through each resistor,and the total current drawn from the battery.

The current $I$ drawn from the $5 \text{ V}$ source will be ............... $A$.

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

From the combination of resistors with resistance values $R_1 = R_2 = R_3 = 5 \ \Omega$ and $R_4 = 10 \ \Omega$,which of the following combinations is the best circuit to get an equivalent resistance of $6 \ \Omega$?

$A$ and $B$ are two points on a uniform ring of radius $r$. The resistance of the ring is $R$. $\angle AOB = \theta$ as shown in the figure. The equivalent resistance between points $A$ and $B$ is . . . . . . .