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8/18/2019 Lesson 2-F5 Physics
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B.Indah : No.15A, 17A, 21A & 41A, Jalan Indah 16/12, Taman Bukit Indah (Tel:
7!2"4#16$%.Au'tin : No. 25!1, 25!2, Jalan Au'tin ei)ht' $/", Taman t Au'tin (Tel:
7!""75%a'ai : No. "!1, "!2, Jalan *em+a' 17, $175, Joho Bahu (Tel: 7!
"$21$#6%*ulai : "$A, Jalan -eak 1, Taman Be'atu, (Tel: 1#!57$"5#6 / 16!722$61#%utiaa a' : "7A, Jalan utiaa a' 1/# (Tel: 16!712"$5 / 16!775$61#%
Name : Teacher: Cheng Wui Leap
Subject : SPM Physics Class : F5 Physics
Chapter
:
Waves Lesson No :
!ate : "#$"$"#Topic : "% &nalysing 'e(lection o( Waves
"%) &nalysing 'e(raction o( Waves
Time : *%"5pm+#%"5pm
Notes:-
Damped Oscillations
"% What is ,amping-
!amping is the in the amplitu,e o( an oscillating system .hen its energy is ,raine, out
as heat energy% The amplitu,e o( an oscillating system .ill gra,ually ,ecrease an, become .hen
the oscillation stops
% What causes ,amping-
+/0ternal ,amping o( the system is the loss o( energy to .
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+ 1nternal ,amping is the loss o( energy ,ue to the in the
system%
)% & graph to sho. ,amping
*% /0ternal Force
To enable an oscillating system to go on continuously2 an (orce must be applie, to thesystem%
5% Force, oscillation
The e0ternal (orce energy to the system% Such a motion is calle, a (orce, oscillation
#% Natural (re3uency
The (re3uency o( a system .hich oscillates (reely the action o( an e0ternal (orce is
calle, the natural (re3uency%
7. Resonance
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'esonance occurs .hen a system is ma,e to oscillate at a (re3uency e3uivalent to its by
an e0ternal (orce% The resonating system oscillates at its 44444444444444444444444444444%
Experiment in Barton’s pendulum
"% The (re3uency o( a simple pen,ulum ,epen,s on the %
% 1n arton6s pen,ulum e0periment2 there are many pen,ulums tie, to the rope% T.o o( the pen,ulum are
o( the same length
)% When pen,ulum oscillates2 all the other pen,ulums are ____________________ to oscillate%
*% ut pen,ulum ! oscillates .ith the ____________________________ 2 ie2 pen,ulum ! resonates
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How does resonance occur in the two pendulum o e!ual len"th#
"% Pen,ulum an, pen,ulum ! are o( the ______________________.
% Fre3uency 7 Fre3uency !
)% There(ore2 pen,ulum causes pen,ulum ! to oscillate at its ______________________.
$ood eects o resonance
"% The tuner in a ra,io or television enables us to ___________________________ .e are
intereste,% The circuit in the tuner is is achieve,2 at the (re3uency
transmitte, by a particular station selecte,% 8ence a stron" electrical si"nal is pro,uce,%
% The o( music pro,uce, by musical instruments such as the trumpet an, (lute is
the result o( in the air%
Bad eects o resonance
%. & bri,ge can collapse .hen the o( its vibration increases as a result o(
______________________________ %
Tacoma Narrows Bridge
The original Tacoma Narrows Bridge roadway twisted and
vibrated violently under 40-mile-per-hour (64 km/h) winds
on the day of the collapse
Exercise
"% 9SPM6"$&$;
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=a> ?n,erline the correct ans.er in the brac@et to complete the sentence belo.%
!amping is a situation .hen the =amplitu,e2 .avelength> o( the oscillation ,ecreases%9" mar@<
=b> State one reason .hy ,amping occurs in the oscillating system%9" mar@<
=c> ase, on !iagram %$er,asar@an 'ajah %2
=i> state the perio, o( the oscillating system%9" mar@<
=ii> .hat is the (re3uency o( the oscillating system-9" mar@
=,> What .ill happen to the perio, o( the oscillating system .hen a heavier loa,is use,-9" mar@<
% 9;*$SPM6""
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=a> =i> Which pen,ulum .ill oscillate .ith the ma0imum amplitu,e-9" mar@<
=ii> ive one reason (or the ans.er in *=a>=i>% 9" mar@<
=iii> Name the phenomenon base, on the ans.er in *=a>=i>% 9" mar@<
=b> Calculate the perio, o( oscillation o( pen,ulum A% 9 mar@s<
=c> Pen,ulum A .ill stop oscillating a(ter a (e. minutes%
Dn !iagram *%2 s@etch the ,isplacement+time graph to sho. the ,amping
process% 9 mar@s<
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%.& Relection o 'a(es
Notes:-
Relection o wa(e
"% Dccurs .hen a .ave stri@es an obstacle%
% The .ave un,ergoes a change in ,irection o( propagation .hen it is re(lecte,%)% The value o( (re3uency =(>2 .avelength =E> an, spee, =v> remain the same a(ter re(lection%
)ncident wa(e : the .ave be(ore it stri@es the obstacleRelected wa(e: the .ave .hich has un,ergone a change in ,irection o( propagation
a(ter re(lection%
i 7 angle o( inci,ent the angle bet.een the ,irection o( propagation o( inci,ent .ave
an, the normal
r 7 angle o( re(lection the angle bet.een the ,irection o( propagation o( re(lecte, .ave
an, the normal%
*aw o Relection:
The angle o( inci,ence2 i is e3ual to the angle o( re(lection2 r%
Relection o plane water wa(es in a ripple tan+
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"% Set up a ripple tan@%
% S.itch on the motor to set the vibrating% 1ncrease the (re3uency o( the .aves by increasing the voltage po.er supply to the motor%
)% Dbserve the re(lecte, .ave by using a stroboscope%
!ra. a ,iagram to sho. re(lection o( .aves%
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Exercise
"% The ,iagram sho.s the stationary pattern o( plane .aves seen through a stroboscope .ith # slits
rotating at a (re3uency o( 5 8B%
What is
a the .avelength o( the .ater .ave- b the spee, o( the .ater .ave-
% & .ave is inci,ent on a plane re(lector P;%
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a What is the angle o( re(lection-
b Complete the ,iagram by ,ra.ing in the re(lecte, .ave%
)% 9SPM6*
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G% 9;)$SPM6I
Fre3uency
C Wavelength
! !irection o( .ave propagation
I% 9;)*$SPM6"
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Which comparison is correct bet.een the inci,ent soun, .ave an, the re(lecte, soun, .ave-
& The re(lecte, angle is bigger than the inci,ent angle
The spee, o( the re(lecte, .ave is the same as the spee, o( the inci,ent .ave
C The .avelength o( the re(lecte, .ave is less than the .avelength o( the inci,ent
.ave
! The (re3uency o( the re(lecte, .ave is lo.er than the (re3uency o( the inci,ent
.ave
"% 9;)$SPM6""
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∴v ∝ E v is ,irectly proportional to E
)% ?se the .or,s2 Kincrease62 ,ecrease6 or Kunchange,6
Characteristics Water .aves passes (rom ,eep
.ater to shallo. .ater
Spee,
Wavelength
Fre3uency
Characteristics Water .aves passes (rom shallo.
.ater to ,eep .ater
Spee,
Wavelength
Fre3uency
*% 8o. ,oes the ,irection o( .aves change .hen:
Water passing (rom the ,eep region to the shallo. region2 the .ater .ave is reracted toward the
normal%
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Water passing (rom the shallo. region to the ,eep region2 the .ater .ave is reracted awa3 (rom
the normal%
4se a ripple tan+
Draw a ra3 dia"ram to show reraction o wa(es.
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