Five identical electric filament lamps numbered $1$ to $5$ are joined in parallel across an ideal source as shown in the figure. When all the bulbs are working, the reading in the ammeter is $3 \,A$. When lamp '$1$' is switched off, the reading of the ammeter is (in $\,A$)

Consider the following two circuits:
$A$: $20$ bulbs are connected in series to a power supply line.
$B$: $20$ bulbs identical to $A$ are connected in a parallel circuit to an identical power supply line.
Identify which of the following is not true.

If $400\; \Omega$ of resistance is made by adding four $100\; \Omega$ resistors of tolerance $5\%$ each,then the tolerance of the combination is .....$\%$

$A$ ring is made of a wire having a total resistance $R_0 = 12\,\Omega$. Find the ratio of the lengths $\frac{\ell_1}{\ell_2}$ of the two arcs between points $A$ and $B$ as shown in the figure,such that the equivalent resistance $R$ of the circuit between these points is $\frac{8}{3}\,\Omega$.

$A$ square-shaped wire with a resistance of $3\, \Omega$ for each side is bent to form a complete circle. The resistance between two diametrically opposite points of the circle in units of $\Omega$ will be:

$A$ 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 . . . . . . .