In domestic electrical wiring,what is the red-colored insulated wire used for?

How does the magnetic field produced by a current-carrying straight wire vary with the distance from the wire?

How is alternating current $(AC)$ different from direct current $(DC)$?

When a light,straight conducting wire is suspended perpendicular to a strong magnetic field and an electric current is passed through it,the magnetic force acting on it is proportional to which of the following?

The laws of electromagnetism tell us that energy can be transferred from one object to another:

$(a)$ An electric current is passed in a horizontal copper wire from east to west. Explain your observations when a compass needle is placed $(i)$ below this wire,$(ii)$ above the wire. Draw inference from your observations.
$(b)$ List the factors on which the strength of the magnetic field due to a straight conductor carrying current depend. How should these be changed to decrease magnetic field at a point?