In the following poem, which does “come to dust” symbolize?

fear no more the heat o’ the sun,
nor the furious winter's rages;
thou thy worldly task hast done,
home art gone, and ta’en they wages
golden lads and girls all must,
as chimney-sweepers, come to dust

the direction of the magnetic field produced by an electric current will change when the direction of the electric current changes. for example : if a current is flowing in a straight length of wire, the magnetic field is described by a concentric circle (using right-hand rule).