Page 55 - Basic Electrical Engineering

which the screw is rotated will indicate the direction of the lines of force
around the conductor.
In Fig. 1.3 (d) has been shown that two current-carrying conductors placed

side by side produce a resultant magnetic field.

1.9.3 Magnetic Field Around a Coil

A coil is formed by winding a wire of certain cross section around a former (a
hollow cylinder made of some non-magnetic material like bakelite, plastics,
etc). Such a coil is often called a solenoid. When current is allowed to flow

through such a coil, a magnetic field is produced by the coil. The direction of
flux produced by a current-carrying coil is determined by applying the right-

hand-grip rule. In Fig. 1.4 (a) is shown a current-carrying coil. If we hold the
coil by our right hand in such a way that the four fingers bend towards the

direction of the current flow through the coil turns, the thumb will indicate
the direction of the resultant flux produced.

Figure 1.4 (a) Right-hand-grip rule applied to determine direction of flux produced by a current-
carrying coil; (b) magnetic field produced by a current-carrying coil