What is the shape of magnetic field lines around a straight current-carrying conductor?

What colour wire is used for earthing or grounding?

$(a)$ In a pattern of magnetic field lines due to a bar magnet,how can the regions of relative strength be identified?
$(b)$ Compare the strength of the magnetic field near the poles and the middle of a bar magnet.

What constitutes the field of a magnet?

Who proposed the principle of electromagnetic induction?

$(a)$ Draw magnetic field lines of a bar magnet. "Two magnetic field lines never intersect each other". Why?
$(b)$ An electric oven of $1.5 \, kW$ is operated in a domestic circuit $(220 \, V)$ that has a current rating of $5 \, A$. What result do you expect in this case? Explain.