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PHYSICS
Figure 30
Pos. 7
: the magnetic field demonstrated in Pos. 6. can be increased, i.e. the lines of Force may become denser
if the wire is spirally wound to form a coil or “solenoid”. Their behaviour is similar to that observed of magnets in
Figure 29 (Pos. 5).
Pos. 8
: if a piece of mild steel is introduced into the energized coil, it will become magnetized and acquires the
ability to attract other bodiesmaking it an electromagnet. If the body in the range of themagnetic fieldwere fixed,
the steel corewould bemoving. This device is used inmany industrial applications because itsmagnetic property
can be controlled. An indispensable feature of the device is that the nucleus is only magnetized when the coil is
energized, the coremust be of iron, as, in the absence of electricity, it loses the ability of attraction and the lines
of force disappear.
6
7
N
S
8
SOUTHof the earth
Electric
current
direction
Fig. 30
1
35
CAMOZZI
>
PHYSICS