Page 535 - The Mechatronics Handbook
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0066_Frame_C20 Page 5 Wednesday, January 9, 2002 5:41 PM
FIGURE 20.6 Motion induced electromotive force.
FIGURE 20.7 Magnetic field generated by current carrying conductor.
FIGURE 20.8 Coil (solenoid) induced magnetic field.
where i is the electric current. If we bend the straight current carrying conductor into a helical coil
(solenoid) with N turns, it will induce a corresponding magnetic field as depicted in Fig. 20.8. If the
length of the coil L is much greater than its diameter D, the flux density follows the right-hand rule and
the magnitude inside the coil is approximately
N
B = µ ---- i⋅ (20.8)
L
where µ = µ r · µ 0 is the permeability of the material inside the coil and i is the current through the
winding. This field can be intensified by inserting a ferromagnetic core into the solenoid by increasing
the permeability. Coil induced magnetic fields is widely utilized in electromagnetic devices for generating
controlled magnetic fields and are often referred to as electromagnets.
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