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FORM 5© COPYRIGHT BY SUPER EDUCATION GROUP (J
CHAPTER 8: Electr!"#$et%&5 Electr'c"l E$er# P*erE+c'e$c
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N S
Direction of magnetic elds
CHAPTER 8: Electr!"#$et
Newton Memory
1. Electromagnet is a temporary magnet consist of a long coil of
insulated copper wire carrying electric current wound on a soft iron
core./temporary magnet produces by the flow of current.
2. The magnetic effect of current is called electromagnetism which
means that electricity produces magnetism.
3.
PREPARED BY JJ MR,EON P"#e -© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)
Permanent Magnet Temporary Magnet
"& it is made of steel
.& the strength of the
magnetic field is
normally constant and is
not adjustable
"& it is made of iron cobalt and
nic!el
.& The strength of the magnetic
field is adjustable or random.
c& both ha"e similar magnetic effect./& both magnet ha"e two pole #North Pole and $outh Pole%
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CHAPTER 8: Electr!"#$et
&.1' Magnetic Effect of a current(carrying conductor
Electromagnets
1. Conductor is a material that can flow ……………………..
2. Electromagnetism is the study of the relationship between ……………….and ………………..
3. ………………………. are produced by electrically charged objects.
4. A bar magnet produces the ………………………around it. raw the pattern of the magnetic fields
produced around a bar magnet below
PREPARED BY JJ MR,EON P"#e 0© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)
current
magnetismelectricity
Electric felds
magnetic felds
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N S
S1t 'r$ cre
I$23l"te/ *'re
4'$2
DC 2344l
*'tc
S1t 'r$ cre
I$23l"te/ *'re
4'$2
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CHAPTER 8: Electr!"#$et
!. "how the deflection of the pointer of the compasses.
#. $agnetic fields also can be produce by an electric current in a wire.
%. Electromagnet is a ………………… magnet. &t is made by winding a coil of insulated wire round a soft
iron core.
'. (sing the diagram) complete the steps to switch on the magnetism effect.
PREPARED BY JJ MR,EON P"#e 6© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)
temporary
Electrom
agnetic
fled
Sot iron
core is
magnetis
Current
ows
S*'tc '2
cl2e/
Attracts
pins
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Direction of magnetic elds
CHAPTER 8: Electr!"#$et
). Magnetic *ield due to a +urrent in $traight ,ire
Method ' using +ompass and -ron filling used to map out the pattern of the magnetic field
1. (sing ight(hand /rip ule) draw the direction of current flows and pattern of magnetic fields formed
2. ight(hand /rip ule states that the thumb of the right hand points to the direction of current flow
and the other four curled fingers points to direction of its ………………….
3. raw the same patterns from the top *iews as follows together with the direction shown by the
compasses.
$eans that a wire carrying current ………….. the plane of paper
$eans that a wire carrying current …………... of the plane of paper
PREPARED BY JJ MR,EON P"#e 7© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)
magnetic
into
out
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CHAPTER 8: Electr!"#$et
E0ercise &.1
1. +wo small plotting compasses , and - are placed near a long straight wire carrying a current as shown.
"how the directions shown by the pointers of the compasses
4. &n the diagram below) the compasses are put under the conductor. Can you draw the direction shown by
compasses and what happen if the compasses are put on the conductor
. Magnetic *ield due to a +urrent in a +ircular +oil
!. raw the direction of current flows and pattern of magnetic fields formed.
PREPARED BY JJ MR,EON P"#e 5© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)
P
Te c!4"22 '2
43t UNDER te
Te c!4"22 '2
43t UNDER te
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CHAPTER 8: Electr!"#$et
#. +he direction of magnetic field also can be determined using the ightand /rip ule.
/ 0otes The field strength is the strongest at the center area because combination from two sources
+he magnetic field strength can be increased by increasing the current flow in the wire.
i adding more battery or cell in the series ciruit
iireducing the resistance by busing the rheostat
iii using a shorter wire
i*using a thicer wire
+he strength of magnetic field of the coil wire increase when
i when the current in the coil increased
iithe number of turn of coil increase
iii a coil with smaller radius is used
+. Magnetic *ield due to a +urrent in a $olenoid
1. $olenoid is combination of coils of wire wounded around on some surface or wounded around an iron
core.
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CHAPTER 8: Electr!"#$et
2. +o chec the poles formed) see from beside of the
solenoid. &f the current flow is cloc!wise) the polarity on
that side is …………………… but) if the current flow is
anti(cloc!wise) the polarity on that side is
……………………
the strength of magnetic field of solenoid increase when
#i% the magnitude of current increase
#ii% the number of turns is increased
#iii% a soft iron core is placed in the solenoid
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North
South
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CHAPTER 8: Electr!"#$et
#i"%the turns of the wire are pushed closer together so that the solenoid become shorter
produce higher field strength.
4.*actors that affects the strength of an electromagnet
15.
+he
higher the number of paper clips attracted to the solenoid shows the …………..….the strength of that
electromagnet.
As a conclusion) fill the table below
Factors Conditions Number of paper clips
attracted
Affects on the strength of
electromagnetic fields
0umber of turns
Electric current
(se of normal iron6core
-nil-(se of soft6iron core
PREPARED BY JJ MR,EON P"#e 8© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)
Manipulated Responding Fixed
0umber of turns Number of paper clips attracted Current) types of core
Current 0umber of paper clips attracted 0umber of turns) types of core
+ypes of core 0umber of paper clips attracted Number of turns, Current
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CHAPTER 8: Electr!"#$et
)pplications of Electromagnet1. +here are many applications of electromagnets. 7abel and describe the figure of each apparatus stated in
the
table
below with its simple wor6frame.
PREPARED BY JJ MR,EON P"#e © COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)
1) Electric bells 2*'tc
-& When the switch is closed, the
current fow will magnetized the sot-
iron core
0& The sot iron armature is pulled
toward electromagnet and hit the
gong
6& At the same time, the contact will
open and stop the current fows. No
electromagnet.
7& The spring mechanism brings the
armature back to its original position
5& The contacts close again and similar
process is repeated.
."tter'e2
21t;'r$
"r!"t3re
c$t"ct
24r'$#2
21t;'r$
cre
#$#
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CHAPTER 8: Electr!"#$et
2) Electromagnetic elays
!) Telephone earpieces//spea"ers
PREPARED BY JJ MR,EON P"#e -<© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)
-& When the switch A is closed, a small
current fows in input circuit will
magnetized the sot-iron core
0& The sot iron armature is attracted
toward electromagnet
6& At the same time, the spring contactclosed
7& A large current fows to high oltage
circuit to operate the electrical
apparatus.
21t;'r$
cret '#
=lt"#e c'rc3't
-& A arying current receied rom the
caller in telephone line
0& The arying current passes through
solenoid and magnetized the sot-
iron core
6& The electromagnet aries in
magnetic strength according to the
eriying current
7& The alloy diaphragm will attract to
electromagnet by arying orce
5& !ound produced as compression and
rareaction o air particles
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CHAPTER 8: Electr!"#$et
5% +ircuit brea!ers
6% 7ifting Magnet
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S1t;'r$
cre
All
/'"4r"#!
Per!"$e$t
!"#$et
2le$'/
automatic switch to
breaks circuit to open when
current becomes too large
It2 4er"te "2 >>>>>>>>>>
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>
-& When the current becomes high
"e#$ short circuit% the electromagnet
strength increase suddenly
0& The iron catch is pulled toward
electromagnet
6& The spring pulling apart the
contacts
7& The circuit will break and the
current fows sto immediatel
24r'$# c$t"ct2
1r! !"'$
2344l
t
32el/
It2 13$ct'$ t >>>>>>>>>>>>>>>>>>>>>>>>>>
-& &pposite poles on the surace will
produces a stronger magnetic 'eld
0& When the current is switched on, the
sot iron core is magnetized to become
a ery powerul magnet
6& (ts lits up iron and steel
7& When the crane has moed to new
location, the current is switched o) and
the sot-iron core is demagnetized
6& The ob*ects will all
moe heay ob*ects or
steel rom place to place
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CHAPTER 8: Electr!"#$et
E0ercise &.1.2
1. A magnetic field is produced by the current in a long straight wire. +he strength of the magnetic field
increases if.
A +he magnitude of the current increases
8 +he distance from the wire increases
C +he length of the wire increases
2. 9hich of the following is true about the magnetic field produced by a current in a flat circular coil.
A &t is uniform inside the coil
8 &t is the weaest at the centre
C &t is the strongest at the centre
+here is no magnetic field outside the coil
3. 9hat is the effect of placing a piece of soft iron core inside a solenoid carrying current
A +he resistance of the solenoid decreases
8 +he current in the solenoid increases
C +he magnetic field becomes stronger
4. An electromagnet is used in these apparatus e0cept
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Nrt Ple
S3t Ple
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CHAPTER 8: Electr!"#$et
A a compass
8 an a.c dynamo
C a mo*ing coil ammeter
a telephone earpiece
!. 9hich electromagnet is the strongest
A 8 C
PREPARED BY JJ MR,EON P"#e -6© COPYRIGHT BY SUPER EDUCATION GROUP (JOHOR JAYA)
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