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MODUL • Fizik TINGKATAN 5

Kawasan medan magnet lemah Kawasan medan magnet kuat
Weak magnetic field region Strong magnetic field region

Bentuk
medan lastik
Pattern of
catapult field

(a) Saling tindakan antara medan magnet yang dihasilkan oleh (a) Ia terdiri daripada gegelung kuprum segi
arus dan medan magnet oleh magnet kekal menghasilkan empat tepat dengan banyak lilitan, di
medan magnet paduan (medan lastik). dalam medan magnet bagi magnet kekal.
The interaction between the magnetic field of the current and It consists of a rectangular copper coil of
the magnetic field of the permanent magnet produces a resultant many turns pivoted in the magnetic field of
magnetic field (catapult field). a permanent magnet.

(b) Medan lastik ini menghasilkan daya gandingan (dalam arah (b) Apabila arus, I, mengalir melalui
yang bertentangan) dan menghasilkan kesan putaran. gegelung , daya putaran akan bertindak
These catapult fields produce a couple of forces (are in opposite ke atas gegelung.
direction) which produces a turning effect. When the current, I, flows through the coil,
a turning force will be acting on the coil.
(c) Gegelung berputar mengikut arah jam.
The coil rotates in a clockwise direction. (c) Gegelung berputar dan penunjuk
terpesong ke kedudukan baru untuk
(d) Apabila gegelung mencapai ke kedudukan menegak, sentuhan menunjukkan magnitud arus, I, yang UNIT 3
antara berus karbon dan komutator terputus, oleh itu tiada daya mengalir melalui gegelung itu.
UNIT 3
putaran memutarkan gegelung itu kerana tiada arus mengalir di The coil turns and the pointer is deflected
dalamnya. to a new position to indicate the magnitude
When the coil gets to the upright position, the contact between the of the current, I, flowing through the coil.
carbon brushes with the commutators is broken. Therefore there is
Penerangan no turning force on it because no current flows in the coil. (d) Apabila tiada arus mengalir, spring
Explanation pengawal menarik gegelung ke
(e) Tetapi gegelung meneruskan putaran disebabkan kedudukan asal semula dan penunjuk
inersianya . terpesong semula ke sifar.
When there is no current flow, the control
But, the coil continues to rotate because of its inertia . spring brings the coil back to its original
position and the pointer goes back to zero
(f) Putaran boleh ditingkatkan dengan: deflection.
The turning effect can be increased by:
• meningkatkan magnitud arus yang mengalir.
increasing the magnitude of the current.

• menambahkan bilangan lilitan gegelung.
increasing the number of turns of the coil.
• menambahkan kekuatan medan magnet dengan
memasukkan teras besi lembut.
increasing the strength of the magnetic field by inserting the
iron core.

• menambahkan diameter wayar.
increasing the diameter of the wire.

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03-Physic F5 2018.indd 95 26/08/2019 11:23 AM