A uniform current is flowing along the length of an infinite, straight, thin, hollow cylinder of radius $R$. The magnetic field $B$ produced at a perpendicular distance $d$ from the axis of the cylinder is plotted in a graph. Which of the following figures looks like the plot?

A solenoid of $1.5 \mathrm{m}$ length and $4 \mathrm{cm}$ diameter possesses $10$ turns per $\mathrm{m}$. A current of $5 \mathrm{A}$ is flowing through it. The magnetic induction at axis inside the solenoid is

What value of current is required to be flown through a circular conducting loop of radius $5.0 \mathrm{cm}$ to nullify the earth's magnetic field?

(given: The earth's magnetic field at a given point is ${\text{0.5×10}}^{\text{-5}}{\text{ Wb m}}^{\text{-2}}$)