What does the given experimental set-up depict?
Choose the correct option accordingly.

If $f: R \rightarrow R$ is defined by $f(x)=[2x]-2[x]$ for $x \in R$,where $[x]$ is the greatest integer function,then the range of $f$ is:

Four resistors $A, B, C$ and $D$ form a Wheatstone bridge as shown in the figure. The bridge is balanced when $C = 100 \Omega$. If $A$ and $B$ are interchanged,the bridge balances for $C = 121 \Omega$. The value of $D$ is (in $\Omega$)

The number of ways that $8$ beads of different colours can be strung as a necklace is

$A$ nucleus at rest splits into two nuclear parts having the same density and radii in the ratio $1 : 2$. Their velocities are in the ratio: (in $: 1$)

Needles $N_1, N_2$ and $N_3$ are made of a ferromagnetic,a paramagnetic and a diamagnetic substance respectively. $A$ magnet when brought close to them will