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igcse physics notesprinted 108 · PDF 108
124 pagesrevision 46936
printed 108 · PDF 108
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108
The magnetic effect of current
The right hand grip rule determines the direction of magnetic field produced
by a current carrying wire.To apply the right hand grip rule, align your
thumb with the direction of the conventional current (positive to negative)
and your fingers will indicate the direction of the magnetic lines of flux. This
is shown in the diagram
The magnetic field produced by a current carrying solenoid is like the
magnetic field produced by a bar magnet. Increasing current through wire
increases the strength of magnetic field and reversing the direction of
current through the wire reverses the direction of magnetic field.
The magnetic effect of current is used in relays.
Flemings left hand rule
If a current carrying conductor is placed in a magnetic field, it experiences a
force due to the magnetic field.
Whenever a current carrying conductor is placed in a magnetic field, the
conductor experiences a force which is perpendicular to both the magnetic
field and the direction of current. According to Fleming's left hand rule, if
the thumb, fore-finger and middle finger of the left hand are stretched to be
perpendicular to each other as shown in the illustration at left, and if the
fore finger represents the direction of magnetic field, the middle finger