Radiasi Benda Hitam
183
Gambar 7.9
a Cahaya sebagai gelombang; b Cahaya sebagai paket-paket
energi.
3 ,E9E6B;27:=26?DE?8CD6?52=2CE2DE=2AEA:;2B
252=29
52?6:C:F:D2C?I2 -6?DE2?=E2C A6BE22?7:=26?=2AEA:;2B0
,63E29=E32?864:=A2525:?5:?8-.+6?I6BEA2: 36?529:D2 :2=E2C?I24
52?CE9E?I2
L C22C6A6BD:CE9E5:52=2D2?EB36B2A2296?6B8:
I2?85:B25:2C:2?6=E2B=E32?8C6D:2A56D: =2+436BC:72DC6A6BD:36?529:D236B252
52=262522?C6:32?856?82?=:?8E?82??I2 -6B?I2D2 3=2 6?I6B2A 52I2 0 52B:
=:?8E?82??I2 6B2A229CE9E3=2:DE 2AEA:;2B52A2D5:2?882A36B36?DE3=2 2B:;2B:
=2AEA:;2BA6BD22252=295E22=:;2B:;2B:=2AE 65E2 ,E9EA:;2BA6BD2252?65E22C:?82C:?8
L52?
L -6?DE2??:=2:A6B32?5:?82?2?D2B2 52I22=BB25:2C:=2AEA6BD2252?=2AE65E2
?CD2?D26:C:F:D2CC63E2936?529:D2252=29 :DE?8=29:?D6?C:D2CB25:2C:I2?85:A2?42B2?2A23:=2
CE9E36?52:DE ,63E293=2=8256?82?;2B:;2B:45:A2?2C2?
252CE9E
L3=2=82:DE62?42B2?B25:2C: 56?82?52I2P
G2DD :DE?8=296:C:F:D2C3=2 =82D6BC63ED
:DE?8=2952I2I2?85:A2?42B2?=69C63E29E3EC I2?85:A2?2C2?9:?882
L E3ECD6BC63ED6:=::
A2?;2?8C:C:452?D6B3E2D52B:3292?56?82? 6:C:F:D2C
6?5262?42B2?B25:2C:56?82?
2H
? 6?52:DED6BEC6?82=2:A62?2C2?C69:?882
CE9E?I22=:=:A2DCE9EC6E=2 -6?DE2?=29
2H
C6D6=29A62?2C2?
Tes Kompetensi Subbab
A
6031-590918.-3
B. Dualisme Gelombang Partikel
1. Sifat Partikel yang Dimiliki Gelombang
252E=2?I232?I27:C:2G2?I2?86?82?882A4292I2C63282: 86=32?8 2=:?:5:A6BE2D56?82?252?I25:7B2C:A=2B:C2C:B67B2C:
B67=6C:52?:?D6B76B6?C:I2?8C6CE2:56?82?C:72DEE86=32?8 2? D6D2A:6D:2A2B27:C:2G2?6?6E2?76?6?2B25:2C:36?529:D2
6767D=:CDB:52?676AD?2CEC:4292I2C63282:86=32?8D:52 52A2D6?;6=2C2?76?6?276?6?2D6BC63ED 6E5:2?E?4E==29
A2?52?82?329G24292I2252=29A2BD:6= ,63282:2?2=8:A6B92D:29 26 2528232BD6BC63ED?523:C266B92D:2?A6B36522?
4292I2;:25:2CEC:2?C63282:86=32?852?C63282:A2BD:6= 6?82? 2CEC: C63282: 86=32?8 4292I2 5:A2?42B2? C63282: B232D2?
86=32?8I2?8?D:?E 52AE?56?82?2CEC:C63282:A2BD:6=4292I2 5:A2?42B2?52=236?DEA26DA26D6?6B8:I2?85:C63ED7D?
,EA2I2?52=63:96292:2CEC:4292I2C63282:A2BD:6=?52 3:C26A6=2;2B:6767D=:CDB:52?676AD?36B:ED
a. Efek Fotolistrik
-+,1-+-+++.- - ,+ +.,-+--.,.--,-+ =6DB?I2?8D6B=6A2C
52B:A6BE22?A=2D=82D6BC63ED5:C63ED6=6DB?7D 6B:CD:G2:?: A6BD222=:5:D6E2?=6968C6A6BD:5:8232B2?A25226
6B2?82DA6B4322?E?DE6?822D:6767D=:CDB:D6B5:B:2D2C D23E?824292A2E52B252?A=2D=82I2?85:C63EDC63282:2D56
6D:22D565:C:?2B:56?82?C:?2BE=DB2F:=6D6=6DB?22?D6B=6A2C 52B:2D5652?36B86B26?E;E2?56C69:?8822BEC6?82=:BA252
B2?82:2? 2?I2?I26=6DB?I2?8D6B=6A2C52A2DD6B=:92D52B::?5:2DB E2D2BECI2?85:DE?;E2?=692A6B66D6B ?6B8::?6D:I2?85::=::
6=6DB? 52A2D 5:D6?DE2? 56?82? 42B2 6A6B36C2B 3652 AD6?C:2= 2?D2B22D5652?2?56C69:?8823652AD6?C:2=36BC:72D6?292?=2;E
2
Gambar 7.10
Skema eksperimen efek fotolistrik. ruang vakum
cahaya
saklar geser tutup
tabung C
T i
i
+ –
+ –
V A
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Mudah dan Aktif Belajar Fisika untuk Kelas XII
184
Gambar 7.11
a Apabila energi kinetik elektron melebihi energi potensial
penghalang, elektron akan dapat mendaki bukit potensial; b Energi
kinetik elektron tidak bergantung pada intensitas cahaya; c Setiap
permukaan memiliki frekuensi f berbeda.
E
k
v
6=6DB? 6BC222?56?82?6?2:2?3652AD6?C:2=A6?E?;E2?;2BE 2A6B66D6B22?6?864:= :2A252CE2DE6D:2;2BE2A6B6D6B
6?E?;E2?82?=36C2B?I26?6B8:AD6?C:2=C2256?82?36C2B6?6B8: :?6D:I2?85::=::6=6DB? :=2:3652AD6?C:2=A252C22D:DE5:C63ED
AD6?C:2=96?D: ?6B8:AD6?C:2= I2?85:36B:2?52A2D5:AB65:C:2?C63282:C63E29
3E:DI2?892BEC5:=6G2D:6=6DB?C6A6BD:A25226 A23:=2 3E:DAD6?C:2=D6BEC5:A6BD:?88:CE2DEC22D2A6B66D6BI2?85:A2C2?8
5:32=:3E:D6?E?;E2?2?82?= ?:36B2BD:6?6B8::?6D:6=6DB? D:52 4EEA =28: E?DE 6=6G2D: 3E:D AD6?C:2= C69:?882 36C2B?I2
AD6?C:2=96?D: 36BC6CE2:2?56?82?6?6B8::?6D:6=6DB?
M 2D2E
2C
M CA6B:6?I2?85:=2E2?=69.378.356?82?6?8E329E329
7B6E6?C:4292I2I2?8;2DE9A252A=2D=822D56:?D6?C:D2C4292I2 52?AD6?C:2=A6?892=2?8A2526767D=:CDB:636B:2?3636B2A2
6C:AE=2?C63282:36B:ED 2 6C2B6?6B8::?6D:2C:E6=6DB?D:5236B82?DE?8A252:?D6?C:D2C
4292I2A6B92D:2?26 3 ,6D:2AA6BE22?=8263EDE92?7B6E6?C::?:ED6BD6?DEI2?8
5:C63ED7B6E6?C:232?8 282B6767D=:CDB:52A2D36B=2?8CE?8
A6B92D:2?26 4 =6DB?6=6DB?5:3632C2?52B:A6BE22?=8292A:BD2?A2C6=2?8
G2DEI2:DEEB2?852B:
M
C6?C6D6=29A6?I:?2B2? 5 -6B:86=32?8D:5252A2D6?;6=2C2?6?82A26?6B8::?6D:
2C:E6=6DB?36BD2329;:27B6E6?C:4292I25:A6B36C2B 2C:=6CA6B:6?D6BC63EDD:5252A2D5:;6=2C2?=69D6B:=2C:
D6?D2?886=32?86=6DB28?6D: 6?EBEDD6B:=2C:6?6B8:I2?8 5:2?5E?886=32?86=6DB28?6D:36BC6CE2:2?56?82?:?D6?C:D2C?I2
A23:=2:?D6?C:D2CC62:?D:?88:6?6B8:86=32?86=6DB28?6D: 22? 6?:?88: AE=2 652? =:CDB: I2?8 5:32G2 86=32?8 6=6DB
28?6D:22?636B:2?82I2A2526=6DB?5:A6BE22?=82 C69:?8826=6DB?6A6B=696?6B8:52B:86=32?8 :26?6B8:I2?8
5::=::6=6DB?4EEA36C2B6=6DB?22?D6B=6A2C52B:A6BE22? =82 6B52C2B2?92=:DEC692BEC?I26?6B8::?6D:6=6DB?36B82?DE?8
A252:?D6?C:D2C4292I2 6925:B2?7B6E6?C:232?8AE?D:5252A2D5:;6=2C2?56?82?D6B:
=2C: CA6B:6?6?E?;E2?329G2C664:=2A2AE?:?D6?C:D2C4292I2 2A23:=27B6E6?C:?I2=63:936C2B52B:A2527B6E6?C:
6767D=:CDB: 22?D6B;25: 6?EBEDD6B:=2C:C692BEC?I2I2?8252252=29:?D6?C:D2C
232?8 6?82? 636B82?DE?82? 6?6B8: 4292I2 A252 :?D6?C:D2C?I2 9E3E?82?=:?62B2?D2B26?6B8::?6D:6=6DB?52?7B6E6?C:86=32?8
6=6DB28?6D:C22C62=:D:5252A2D5:;6=2C2? 6?EBED 168 .378.3 C6E2 6?6B8: 7D? 5:36B:2? 6A252
6=6DB?52?:?:6?I63232?7D?=6?I2A 236BA2?52?82?329G2 E2?DE6BEA22?C:72D86=32?8:DEC6?5:B: 6?EBED?I24292I2
Sumber
: Fisika untuk Sains dan Teknik Tipler
2 3
2 4
6 8
f f
f C
e
N
a
K
10
14
Hz energi potensial
gelombang eV
–V V
I intensitas
tinggi intensitas
rendah
2
3
4
1
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Radiasi Benda Hitam
185
D6B5:B:2D2CA26DA26DI2?85:C63EDC63282:7D? D?7D?6BEA22? A2BD:6=I2?8D:5236B2CC2I2?85:C6B2A52?5:A2?42B2? ?6B8:I2?85::=::
=697D?C2256?82?E2?D2I2?85:6E22?=69=2?4I2:DE 56?82?252=29?CD2?D2=2?452?252=297B6E6?C:86=32?8
6=6DB28?6D: :?CD6:?52A2D6?;6=2C2?C642B2C6AEB?292C:=6767D=:CDB:
292I2I2?8;2DE95:2D2C=825:=E:C2?C63282:B6?D6D2?7D?I2?8 6?E3EA252=82C6D:2A7D?6?E3E6=6DB?52=2=82
252A6B:CD:G2DE3E2?D6BC63ED7D?636B:2?C6=EBE96?6B8:?I2 6A2526=6DB?52?7D?:DEC6?5:B:6?;25:=6?I2A
?6B8:I2?85:A6B=E2?E?DE6=6A2C2?5:B:52B:A6BE22?=82 5:C63ED7E?8C:6B;2 .?DE;6?:C=82I2?836B3652D6?DE?I27E?8C:
6B;222?36B3652AE=22B6?2A6B36522?6?6B8::2D2?D2B26=6DB? 52?:?52=2=82 25:E?DE=82D6BD6?DE36B=2E
M :27B6E6?C:7D?=63:936C2B52B:A2527B6E6?C:232?86=63:92?
6?6B8:I2?85:D6B:26=6DB?:DE22?6?;25:6?6B8::?6D:6=6DB? 2
M
M Keterangan:
?CD2?D2=2?4P
M
C 7B6E6?C:86=32?84292I2J
7B6E6?C:232?8J :25:3E2D52=2C63E29D236=7E?8C:6B;27D=:CDB:3636B2A2;6?:C
=823:C25:=:92D52=21
1 eV = 1,6 × 10
–19
J
Ingatlah
1
E?8C:6B;2=6DB?A252636B2A282 6C:E
C 2=:E
2DB:E 2
2C E
-63282 E
6B2 8
=2D:?2 D
4,2 23,
93,7.6
Efek fotolistrik selain memiliki peranan penting dalam teori foton
pada cahaya, juga memiliki banyak sekali aplikasi dalam kehidupan
sehari-hari. Sebagai contoh adalah alarm pencuri dan pembuka
otomatis yang juga menggunakan sirkuit fotolistrik. Ketika seseorang
menghalangi sinar yang dipancarkan, penurunan arus listrik dapat
mengaktifkan saklar sehingga bel berbunyi atau pintu terbuka.
Biasanya sinar yang digunakan adalah sinar ultraviolet dan inframerah
karena kedua sinar ini tidak terlihat.
The photoelectric effect, besides playing an important historical role
in confirming the photon theory of light, also has many practical
applications. Burglar alarms and automatic door openers often make
use of the photocell circuit. When a person interrupts the beam of light, the
sudden drop in current in the circuit activates a switch which operates a
bell or opens the door. UV or IR light is sometimes used in burglar alarms
because of its invisibility.
Sumber
: Physics for Scientist Engineers
Informasi
untuk Anda
Information for You
B6E6?C:232?8CE2DE3292?P J :23292?D6BC63ED5:C:?2B:56?82?C:?2B
I2?86:=::7B6E6?C:
P JD6?DE2?36C2B6?6B8::?6D:6=6DB?I2?8
D6B=6A2C52B:A6BE22?=82D6BC63ED ;
2 2
P
M
C
P JMP
J P
M
CP JP
M
;E=6
Contoh
7.6
Sumber
: Physics, 1993
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186
2=:E5:C:?2B:56?82?4292I2E=DB2F:=6DI2?8A2?;2?886=32?8?I2
K :27E?8C: 6B;22=:E
6D6?DE2?=29?:=2:AD6?C:2=96?D:A252A6B:CD:G26767D=:CDB:
D6BC63EDP
M
C ;
:6D29E: K
P
M
6
6P
M
C P
M
?6B8::?6D:2C:E6=6DB? 2
2
C C
P
M
6E5:2?8E?22?6723?C69:?882 2D2E
25:AD6?C:2=96?D:A2526767D=:CDB:D6BC63ED252=29
b. Efek Compton
