2. ELECTROMAGNETISM INDUCTION THE PRODUCTION OF AN ELECTRIC
CURRENT BY A CHANGING MAGNETISM FIELD IS CALLED ELECTROMAGNETISM
INDUCTION THE INDUCED CURRENT IS PRODUCED ONLY WHEN THERE IS
RELATIVE MOTION BETWEEN THE CONDUCTOR/COIL AND THE MAGNETISM FIELD
LINES. THE INDUCED CURRENT IS PRODUCED WHEN a) A conductor cuts
across a magnetism flux b) There is a change in magnetism flux
linking a coil or a circuit 3. RELATIVE MOTION There is a relative
motion between two objects if the two objects are getting closer or
futher apart When two objects are moving at the same speed in same
direction, there is no relative motion because the distance between
the two objects does not change 4. INDUCED CURRENT AND INDUCED
ELECTROMOTIVE FORCE Electromotive force is required to drive the
current in a closed circuit. Induced electromotive force(induced
e.m.f.) is produced between the end of the moving conductor or the
solenoid. When galvanometer is connected to form a closed circuit,
the pointer of the galvanometer moves when the magnet is moved back
and forth inside the solenoid.(refer to figure 1) The induced
e.m.f. ois responsible for driveng the current flow in the closed
circuit through the galvanometer. The greater the induced e.m.f. is
the greater the induced current. the magnitude of the induced
e.m.f. and direction of the induced current can be detemined by
application of the laws of electromagnetism induction. 5. LAWS OF
ELECTROMAGNETISM INDUCTION There are 2 principal laws of
electromagnetism induction: a) Faradays law b) Lenzs law 6. LENZS
LAW Lenzs law state that an induced electric current always flows
in such a direction so as to oppose the change(or motion)causing
it. Lenzs law is a form of the law of conservation of energy. It
can be explained by the principle of conservation of energy. a)
When the magnet is moved towards the solenoid, current is induced
in the solenoid. Why does it occur? Eletrical energy cannot be
created without any form of work being done. Hence, the P must be
induced to become the north pole so that a force of reputation
exists between the solenoid and the magnet. b) When the magnet is
moved away from the solenoid, the end P is induced to become the
south pole so that the force of attraction exists between the
solenoid and the magnet. c) Therefore, when a magnet is moved
towards or away from a solenoid, work must be done to overcome the
opposing force. d) The work done is converted into electrical
energy which creates the induced current. 7. FARADAYS LAWS Faradays
law states that the magnitude of the induced e.m.f. is directly
proportional to the rate of change of magnetism flux linkage in
solenoid or the rate at which a conductor cuts through the
magnetism flux. The induced e.m.f. increases when the rate of
change of flux increases. hence., the induced current is increased
when The induced e.m.f. increases when the number of turns
increases because an e.m.f. is induced in each turn of wire. 8.
FLAMINGS RIGTH-HAND RULE(DINAMO RULE) The direction of a current
induced in a conductor moving at rigth angles to and cutting across
a magnetic flux can be determined with flemings rigth hand rule. If
the first finger, second finger and the thumb of the rigth hand are
held at rigth angles to each other, with the First finger
indicating the direction of the Field(B), the thumb indicating the
direction of the Motion of the conductor, then the second finger
points in the direction of the induced Current(I). 9. Applicationof
electromagnetiismionduction Direct Current Generator and
Alternatives Current Generator Operating Principle of a Direct
Current Generator Operating Principle of an Alternatives Current
Generator Moving Coil Microphone 10. DIRECT CURRENT GENERATOR AND
ALTERNATIVES CURRENT GENERATOR The direct current generator(d.c.
dynamo) and the alternating current generator(a.c. dynamo) make use
of eletromagnetism induction to produce a current. Direct current
generator The construction features are similar to an letric motor.
The difference is that the coil of the generator is not connected
to an bettery but to a load(e.g. resistor or bulb) The coil is
rotated to produce a current. Alternating current generator The
generator consisting of a rectangular coil rotating in a magnetiic
field. The two ends of the coil are connected to two slip rings
which rotate with the coil. Two spring-loaded carbon brushes are in
contact with the slip rings. 11. CREATED BY: PROF DR. SYAFIQ WAHAB
DR. PUTRA DR. KHAIRUN DR. AMIRA DR. SYAMIERA
