The value of current $I$ in the given current distribution is (in $A$)

In the given circuit,the electric currents through $15 \Omega$ and $6 \Omega$ resistors respectively are:

In the arrangement of resistors shown in the diagram,the potential difference between $B$ and $D$ will be zero when the unknown resistance $X$ is ............... $\Omega$.

State the principle of a Wheatstone bridge.

The equivalent resistance between the points $A$ and $B$ in the following circuit is $\frac{x}{5} \Omega$. The value of $x$ is . . . . . . .

The equivalent resistance between points $A$ and $B$ is ............ $\Omega$.