What is the shape of the magnetic field lines inside a solenoid?

In domestic electrical wiring,which color of insulation is typically used for the neutral wire?

$A$ uniform magnetic field exists in the plane of paper pointing from left to right as shown in Figure. In the field,an electron and a proton move as shown. The electron and the proton experience:

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

No two magnetic field lines can intersect each other. Explain.

The following diagram shows two straight wires carrying current. Copy the diagram and draw the pattern of lines of force around them and mark their directions.