Electrodynamics

13

13.1 Introduction ESCFO

In Grade 11 you learnt how a magnetic field is generated around a current carrying con-

ductor. You also learnt how a current is generated in a conductor that moves in a mag-

netic field. This chapterdescribes how conductors moving in a magneticfield are ap-

plied in the real-world. See introductory video:VPpjl at http://www.everythingscience.co.za

13.2 Electrical machines - generators and motors

ESCFP

We have seen that when a conductor is movedin a magnetic field or when a magnet

is moved near a conductor, a current flows in the conductor. The amount of current

depends on the speed at which the conductor experiences a changing magnetic field,

the number of turns ofthe conductor and the position of the plane of the conductor

with respect to the magnetic field. The effect of the orientation of the conductor with

respect to the magneticfield is illustrated in Figure 13.1.

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top view

front view

(a) (b) (c) (d)

Figure 13.1: Series of figures showing that themagnetic flux through aconductor is

dependent on the anglethat the plane of the conductor makes with the magnetic field.

The greatest flux passesthrough the conductorwhen the plane of theconductor is

perpendicular to the magnetic field lines as in (a). The number of fieldlines passing

through the conductordecreases, as the conductor rotates until it isparallel to the

magnetic field (c).