Magnetic Field Around a Wire Carrying Electric Current

To prove that arround a wire carrying electric current there is a magnetic field, then a physicist named Hans Cristian Oersted (1777-1851), made an expriment in 1820 by showing that the compss’s needle always changed position when it lay near a condctr wire conducted with electric current.

Based on Oersted’s experiment, it can be concluded that around a wire carrying electric current a magnetic field is found; the direction of magnetic field depends on the direction of electric current passing through the conductor wire; the farther from the wire carrying current, the smaller the magnetic field strength; and the bigger the electric current, the stronger the magnetic field.

The direction of magnetic field lines around a wire carrying current can be determined by two rules, those are;

1.    Right-hand rule for electric current
       (a)    The thmb shows the direction of electric current
       (b)    The other four fingers show the direction of magnetic field lines around the wire that go
               around the conductor wire

2.    The clockwise screw rule
        (a)    The direction of screw turning detrmine (indictes) the direction og magnetic field
        (b)    The linear direction of screw determines the direction of current.

Reference:
Irawan, Etsa Indra dan Sunardi. 2008. Pelajaran IPA-Fisika Bilingual untuk SMP/MTs. Kelas IX. Bandung: CV.Yrama Widya.