If $z$ is a complex number satisfying $|z - 3| \leq 5$,then the range of $|z + 3i|$ is (where $i = \sqrt{-1}$)

What is the pressure on a swimmer $20 \, m$ below the surface of water in $atm$?

Given below are two statements:
Statement $I$: $[CoBr_{4}]^{2-}$ ion will absorb light of lower energy than $[CoCl_{4}]^{2-}$ ion.
Statement $II$: In $[CoI_{4}]^{2-}$ ion, the energy separation between the two sets of $d$-orbitals is more than $[CoCl_{4}]^{2-}$ ion.
In the light of the above statements, choose the correct answer from the options given below:

$A$ circular conducting loop of radius $R$ carries a current $I.$ Another straight infinite conductor carrying current $I$ passes through the diameter of this loop as shown in the figure. The magnitude of force exerted by the straight conductor on the loop is

The ratio of diameters of two wires of the same material is $n : 1$. The length of the wires is $4\, m$ each. On applying the same load,the increase in length of the thin wire will be

If a wire of length $L$ forms a loop of radius $R$ and has $n$ turns,find the magnetic field at the centre of the loop if the current flowing in the loop is $I$.