Mudah dan Aktif Belajar Fisika untuk Kelas XII
34
B9
K 4571
-CD;C5A17DB1C;9C1=5=25A9;1
9C1C5A175AC1=1
41B5C5ADBG1 41D DCD; 9C5A65A5B9 =99=D= 9C5A65A5B9 45BCAD;C96
1BC92917171:9;19B5C571875?=217340 9411C 49CD9B;1B52171925A9;DC
B9 K
4571 -CD;7515AC1=1;9C1=5=25A9;19C1751;54D1
41B5C5ADBG1
2. Menentukan Jarak Pita Terang ke-m atau Pita Gelap ke-m dari Terang Pusat
141 5=2181B1 B525D=G1 C518 49B52DC;1 218F1 ?1 9C5A65A5B91411G1A25AD19C1C5A17419C1751 5A81C9;1
3 9C1411C=55CD;1;54D4D;19C1C5A17;51C1D 9C1751;51411G1A 5A81C9;1;5=2193
58
;1A51:1D8529825B1A41A9141 BD4DC
25A919B171C ;539 -CD;BD4DCG17B171C;5391;125A1;DB9
C1 1A9
3
;9C1411C=55CD;1218F1 B9
C1 K
-CD;9C1C5A17=1BD;;1 340 9;5340 9 B589771495A?58
K -CD;9C1751=1BD;;1 340 9;5 340 9
B589771495A?58 K
5C5A171 :1A1;1C1A35181411G1A
:1A1;C5A17
751;541A9DB1C :1A1;1G1A;53518
1:1775?=2173181G1 11=8199
Tantangan
untuk Anda
Seberkas cahaya monokromatis dijatuhkan pada dua celah sempit
vertikal berdekatan dengan jarak d = 0,01 mm. Pola interferensi yang
terjadi ditangkap pada jarak 20 cm dari celah. Diketahui bahwa jarak
antara garis gelap pertama di sebelah kiri ke garis gelap pertama
di sebelah kanan adalah 7,2 mm. Hitunglah panjang gelombang
berkas cahaya tersebut.
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Gelombang Cahaya
35
-CD;=55CD;11:1775?=217B91AG1749131A;1?581=D9:1A 1CA9D=B91A99495F1C;11414D13518G1725A:1A1;== 141:1A1;=5C5A
41A93518491B171G1A 9;181B99C5A65A5B91411G1A495A?58:1A1;71A9BC5A17 DB1CB1=194571;59=114118==25A11;181:1775?=217B91A1CA9D=
C5AB52DC 7
9;5C18D9 ==L
K
= ==L
K
= =
k = =
L
K
I 1491:1775?=217B91A1CA9D=14118 I
Contoh
2.1
141B52D185A3?2119C5A65A5B9497D1;14D13518B5=9C 1A1;1C1A1;54D1 35189CD
==41495C1;;1141:1A1;
=;51G1A71A9B7515AC1=141A9DB1C
G17:1A1;G1== 9CD7181:1775?=2173181G1G1 7
==
L
K
= =
==L
K
=9C5A65A5B9751 1A9340 9
495A?58
=K =
=
= K
L
K
=
L
K
= I 1491:1775?=2173181G1G114118 I
Contoh
2.2
3. Interferensi oleh Lapisan Tipis
5=1CD13181G1=1C181A9?58G174931=DA 4571 19A 1;1 =5=5A981C;1 71A9B71A9B 25AF1A1 141 =9G1;
+5;CAD=F1A199=5=5A981C;1141G1 ?58 19B1=9G1;G17C99B9CD C5A65A5B9C5AB52DC411C25AD19C5A65A5B9
=1;B9=D==1DD9C5A65A5B9=99=D= C5A65A5B91C1A175?=217 G17491CD;1?5819B1C99B49CD:D;;11413
+525A;1BB91A41C17=5751919B1C99B4571BD4DC41C17 1;149291B;141B521791179491CD;1;5=219;55A=D;11
+91A G17 491CD;1 495F1C;1 141 B52D18 5B1 ?B9C96 41 496?;DB;149C9C9; 5A;1B3181G149C9C9;=5AD1;181B99C5A65A5B9
25A;1B 3181G1 41
4571 14118 25A;1B 3181G1 G17 491CD;117BD741
1411825A;1B3181G1G17=5711=9
5=291B1C5A5298418DD;5=D491491CD;1
Gambar 2.4
Interferensi oleh lapisan tipis. P
D A
B C
i
d n
r lensa
lapisan tipis
1 2
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Mudah dan Aktif Belajar Fisika untuk Kelas XII
36
+59B98 9C1B1 ?C9; G17 49C5=D8 ?58 B91A 41C17 89771 =5:149B91A1CD;541B91A1CD;5
14118
K K
K
457114118945;B291B19B1C99B41 9B1;1C521 19B114118=1;13?BB589771
3?B
41B94571
C1B589771 3?B
K
C1B9 3?B
K
B9 B9 3?B
571=577D1;16-60..+64C5C175=291B13181G1 G1;9B9B9495A?58B59B98:1A1;C5=D8;54D1B91A=5:149
3?B
K B9
3?B
3?B
KB9
3?B
3?B 3?B
K +D1G1C5A:1499C5A65A5B9=1;B9=D=49C9C9;
81ADB=5AD1 ;1;591C141A91:1775?=217 ;1C5C19B91A1CD49
=5711=95AD218161B5 =1;1
1;1=5:149 1C1D
K C5A65A5B9=1;B9=D=B91A1CD14119B1C99B1;1=5=5D89
5AB1=11 3?B
K 4571
340 925A1;DDCD;945;B291B19B1C99B529825B1A 41A91C1D
41DDCD;=5=5A?589C5A65A5B9=99=D=;54D1B91A1CD 81ADB=5=99;9254161B5
=1;1
C5A65A5B9=99=D=411=1A181CD=5=5D895AB1=11 3?B41
1C1D 3?B
K 4571945;B291B
41=5=5D89BG1A1C 41
1C1D 41
Gambar 2.7
Interferensi oleh lapisan minyak yang tipis.
Sumber: www.instckphoto.com
Gambar 2.6
Interferensi oleh lapisan busa sabun yang tipis.
Sumber: www.funsci.com
,5CD;1C52119B1=99=D=G17492DCD8;1BD1G1C5A:1499C5A65A5B9141B52D18 19B1C99BG17=5=99;9945;B291B
45711:1775?=217 I
Contoh
2.3
Gambar 2.5
Interferensi oleh busa sabun.
Sumber: www.designprodygzone.com
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Gelombang Cahaya
37
Tugas Anda 2.1
Coba Anda perhatikan kembali Gambar 2.5. Gelembung tersebut
sebenarnya berwarna-warni. Mengapa demikian? Anda dapat
mencari jawabannya dari buku referensi atau internet.
7
C5A65A5B9=1;B9=D=14119B1C99B=5=5D895AB1=11 3?B
3?B
+D1G1C52119B1=99=D=B5C99BC99BG1=1;1 413?BB589771495A?58
I I
I
149C52119B1C99BG17492DCD8;114118
I
,5CD;11:1775?=217B91AG17497D1;1:9;1C5A:1499C5A65A5B9=99=D= ?A45;54D141A919B1C99B49D41A14571;5C5211 =BD4DC291BJ41
945;B291B19B1 7
571=577D1;1340 9495A?58 3?B
=3?BJ =
1491:1775?=217G17497D1;114118=
Contoh
2.4
Kata Kunci
• interferensi • sinar monokromatis
• interferensi maksimum • interferensi minimum
Tes Kompetensi Subbab
A
3,-0..6-6.5+0 1G1749=1;BD49C5A65B93181G1
+52D183518714125A:1A1;==49251;173518 41141:1A1;
=5C5A495C1;;1B52D181G1A 518
49B91A94D1B91A=??;A?=1C9B45711:17 75?=217=41= 5A11;18:1A1;71A9B
C5A17?A45;55=1C;54D1B91A1411G1A +525A;1B3181G1=55F1C94D13518B5=9CG17B1CD
B1=11925A:1A1;== 1A1;3518;51G1A=5C5A 41:1A1;1C1A14D171A9BC5A171411G1A14118
L
K
3= 5A11;181:1775?=2173181G1 G17497D1;1
-CD;=57D;DA1:17B91A=5A18491;D;1 5A3?211B52171925A9;DC
+91A 29AD 4571 1:17 75?=217 = 49:1CD8;1 C571; DADB 141 3518 7141 ?1
9C5A65A5B9C5A:1491411G1AG1725A:1A1;
=41A9 3518 1A9BC5A17?A455AC1=125A:1A1;==41A9
71A9BC5A17DB1C +5C5189CDB91A=5A1849:1CD8;1 1413518 ,5AG1C171A9BC5A17?A455AC1=125A:1A1;
==41A971A9BC5A17DB1C ,5CD;1181:17 75?=217B91A=5A189CD
+52D1819B1C99B=5=99;9945;B291B
497D1;1 DCD; =5981C 75:11 9C5A65A5B9 9;1 1:17
75?=217G1 IC5CD;1C521=99=D= 19B1C5AB52DCBD1G1C5A:1499C5A65A5B9
B. Difraksi Cahaya
14151:1A175C1A14175?=2174951BC518492181B218F1 75?=21719AG17=55F1C9B52D185781174571B52D183518
B5=9C1;1=5711=95CDA1 5?=217G1741C17411C25A25?; B5C518=51D93518C5AB52DC 5=25?;175?=217G1749B5212;1
?58141G157811725AD1351849B52DC496A1;B975?=217 +1=1 81G1457175?=2173181G1G17495F1C;1141B52D183518
B5=9C:D711;1=5711=95CDA1
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