Halaman
A. CahayaB. PemantulanCahayaC. PembiasanCahayaD. Alat-Alat OptikCahaya dan Optika,5C91@81A9=1>DB91C941;1;1>@5A>18C5A<5@1B41A93181H1 5>4125>4149B5;5<9<9>7>4141@1CC5A<981C;1A5>1141>H13181H1 181H1:D71H1>7=5=2D1C>4141@1C=5<981C21H1>71>>414935A=9> &D>7;9>>41@5A>18=5=5A81C9;1>;131B@9?>@141=?29<1C1DB5@541=?C?A $131B@9?>@141=?29<41>B5@541=?C?A=5AD@1;1>B52D1835A=9>35=2D>7H1>7497D>1;1>@5>75=D49D>CD;=5<981C<1<D<9>C1B4925<1;1>7=?29<1C1DB5@541=?C?A 5>71>=5<981C;131B@9?>@5>75=D4941@1C25A25<?;25A85>C91C1D=5>418D<D9;5>41A11><19>45>71>1=1> )141;131B@9?>C5A:149@5=1>CD<1>3181H1B589>771>4141@1C=5<981C21H1>71>25>4125>41H1>725A1414945@1>>H1 1@1C;18>41=5>7945>C969;1B9B961CB961C21H1>71>@14135A=9>;131B@9?>,5<19>35A=9>35=2D>725A41B1A;1>25>CD;>H11414D1:5>9B35A=9><19>>H1H19CD35A=9>41C1A41>35A=9>35;D>7 1@1C;18;54D135A=9>9>9=5>5ADB;1>3181H11719=1>1B961CB961C21H1>71>>H1>4141@1C=5>5>CD;1>:1F121>@5AC1>H11>@5AC1>H11>C5AB52DC41<1=2129>9 (<58;1A5>19CD@5<1:1A9<182129>945>71>219; 107•menganalisis alat-alat optik secara kualitatif dan kuantitatif;•menerapkan alat-alat optik dalam kehidupan sehari-hari.Setelah mempelajari bab ini, Anda harus mampu:menerapkan prinsip kerja alat-alat optik.Hasil yang harus Anda capai:Pengemudi memanfaatkan pemantulan cahaya pada cermincembung kaca spion.Bab6Sumber: Dokumentasi Penerbit
108Mudah dan Aktif Belajar Fisika untuk Kelas XA. Cahaya,19>B41>C5;>?<?79B5<1<D=5=21F1>41D>CD;=1=@D=5=181=91<1= !1<9>949B5212;1>B19>B41>C5;>?<?79B5<1<D=5=25A9@5>75C18D1>21ADB5AC19>BCAD=5>21ADH1>7=1=@D=5>7D>7;1@A181B91A181B911<1=B5;1<9@D>75:1<11<1=H1>7B5=D<1491>771@C941;=D>7;9>C5AD>7;1@ 5>?=5>11BCA?>?=941@1C<529821>H1;C5AD>7;1@;1A5>1C5AB5491>H1C5<5B;?@1C1DC5A?@?>7H1>7<5298219;41A9@141B525<D=>H1 $5=1:D1>41>@5>5=D1>41<1=29?<?79=?45A>C941;41@1CC5A:149:9;1C941;141=9;A?B;?@ 1719=1>11<1C1<1C?@C9;C5AB52DC25;5A:141>=1=@D=5>7D>7;1@A181B911<1= 1<1=2129>91;1>492181BB5:D=<188D;D=B5AC1@A9>B9@?@C9;175?=5CA9@5=1>CD<1>41>@5=291B1>H1>749C5A1@;1>41<1=2525A1@11<1C?@C9; 1. Teori-Teori tentang Cahaya5A9;DC1;1>49:5<1B;1>2525A1@1C5?A9C5>C1>73181H1 a.Teori Partikel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es Kompetensi Awal @1@5A25411>1>C1A121H1>71>=1H141>21H1>71>>H1C1
1719=1>1B961C21H1>71>@14135A=9> @1H1>749=1;BD445>71>@5=291B1>9>45;B291BA5<1C9641>9>45;B291B=DC<1; 1719=1>1B961C<5>B135=2D>741><5>B135;D>7C5A8141@25A;1B3181H1H1>7=5<5F1C9>H1 ,52DC;1>2525A1@1=1>611C<5>B1H1>7>41;5C18D9 To k o hSeorang fisikawan Belanda,Christian Huygens dilahirkan diDen Haag, pada 14 April 1626.Ayahnya seorang diplomat dansastrawan. Pada 1666, iamemberikan sumbangan pentingtentang ilmu Matematika,Astronomi, Optik, dan Mekanika,yang membuat namanya terkenalsebagai ilmuwan penting di Eropa.Pada 1655, Huygens menyempurna-kan teleskopnya yang cukup kuatuntuk menemukan sebuah satelitPlanet Saturnus, kemudian diberinama Titan. Pada awal 1660-an iamenemukan lensa pelihat (okuler)yang terdiri atas gabungan lensa,guna mengurangi gangguan warnayang timbul akibat penggunaanlensa-lensa non-akromatik, lensa inimasih dipakai sampai sekarang.Christian Huygens(1580 – 1626)Sumber:Jendela Iptek, 1997
109Cahaya dan Optika@5>5<9C91>>H1 (9621=5>H9=@D<;1>218F1@141D=D=>H13181H1C5A49A91C1BB5;D=@D<1>@1AC9;5<H1>749B52DC,.-1/ )"/b.Teori Gelombang)141 7:*(1525ADB181=5<1F1>-5?A9)1AC9;5<45>71>=5>H1C1;1>218F13181H1=5AD@1;1>75<?=21>7H1>725A75A1;45>71>;535@1C1>C5AC5>CD41<1==549D=5C5A &5>DADC7:*(15C9C9;C9C9;@141=D;175<?=21>7H1>7=5A1=21C41@1C491>771@B52171975<?=21>721AD )14175<?=21>7<9>7;1A1>=D;175<?=21>7>H125AD@1<9>7;1A1>B541>7;1>@14175<?=21>741C1A=D;175<?=21>7>H125AD@171A9B<DADB -5?A975<?=21>741@1C=5H1;9>;1>218F1<1:D3181H141<1=19A<5298<1=21C41A9@14149D41A1 5>71>45=9;91>=5>DADC7:*(15-5?A9)1AC9;5< (96217D7DA 01<1D@D>45=9;91>C5?A975<?=21>7C941;=1=@D=5>:5<1B;1>C5>C1>7@5A1=21C1>3181H125AD@171A9B<DADB $5<5=181>9>9H1>7=5>H5212;1> (9621C941;B5CD:D45>71>C5?A975<?=21>7 -5?A97:*(15=1=@D=5>5=D;1>AD=DBAD=DB@5=291B1>41>@5=1>CD<1>3181H145>71>B1>71C=5=D1B;1> B. Pemantulan Cahaya 121>79<=D@5>75C18D1>C5>C1>73181H1H1>7=5=@5<1:1A9B961CB961C@5A1=21C1>3181H1B5@5AC9@5=1>CD<1>@5=291B1>B5AC1@A9>B9@:1<1>>H1B9>1AB9>1A49B52DC,-0&( $",*"0.& 1<1=?@C9;175?=5CA93181H141@1C4971=21A;1>45>71>B9>1A25AD@171A9BH1>7C571;<DADB45>71>=D;175<?=21>741>C941;B5@5>D8>H1=5=@5A89CD>7;1>B961C75<?=21>741A93181H1C5AB52DC )5>771=21A1>3181H1B521719B9>1A25AD@171A9B<DADBC941;41@1C49C5A1@;1>41<1=,-0&( #&/&/)141?@C9;169B9B3181H181ADBB5@5>D8>H149@1>41>7B52171975<?=21>7;1A5>1565;565;9>C5A65A5>B941>496A1;B9>H1B1>71C4?=9>1> 1.Pemantulan Baur dan Pemantulan Teratur)141D=D=>H1B5C91@@5=D;11>25>4141@1C=5=1>CD<;1>3181H1H1>7:1CD8@141@5A=D;11>25>41C5AB52DC )5A=D;11>25>4141@1C25AD@1@5A=D;11>;1B1A1C1D81<DB ,525A;1B3181H1H1>7:1CD8@14125>4145>71>@5A=D;11>;1B1A1;1>49@1>CD<;1>45>71>1A18B9>1A@1>CD<H1>7C1;C5A1CDA )5=1>CD<1>9>949B52DC-"* +01) + 1.@5A81C9;1>$0%$4
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)5=1>CD<1>3181H1@141@5A=D;11>25>41C941;B5=21A1>7=5<19>;1>=5=9<9;9;5C5A1CDA1>B5BD1945>71>8D;D=8D;D=@5=1>CD<1> Tes Kompetensi Subbab A(4-$.$1/$+'$/$0%7.7/$6,+$1 &5>DADCC5?A9@1AC9;5<41>C5?A975<?=21>71@1;183181H19CD (962125A@5>41@1C218F13181H1=5AD@1;1>@1AC9;5< 5A9;1>@5>:5<1B1>=5>75>19C5?A99>945>71>;1<9=1C>41B5>49A9 1719=1>189@?C5B9B7:*(15B589>77149125A@5>41@1C218F13181H1=5AD@1;1>75<?=21>7 @1;5<5=181>C5?A975<?=21>7H1>7=5=2D1C (9621=1B98C941;B5CD:D45>71>C5?A99CD &5>DADC>41491>C1A1C5?A9@1AC9;5<41>C5?A975<?=21>7=1>1;18H1>7@1<9>725>1AKata Kunci•partikel•gelombangGambar 6.2Pemantulan teraturGambar 6.1Pemantulan baur
110Mudah dan Aktif Belajar Fisika untuk Kelas XAktivitas Fisika 6.1kartonsinarpantulsinar datangpointerinframerah2.Hukum Pemantulan#9;1@141.6,8,6$5,5,.$
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112Mudah dan Aktif Belajar Fisika untuk Kelas X(<58;1A5>1B9>1A@1>CD<B1=145>71>B9>1A41C1>7=1;1
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113Cahaya dan OptikaGambar 6.8Bagian-bagian cermin cekungf = jarak fokusR = kelengkungan cerminRfOBFPa)b)c)PFOGambar 6.9Sinar istimewa pada cermincekungGambar 6.10Pembentukan bayangan di ruang IIIAB pada cermin cekungOB'FPA'ABIIIIII5A41B1A;1>$0%$4
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114Mudah dan Aktif Belajar Fisika untuk Kelas X 7%71*$1$16$4$-$4$.)2.75'$1-$4,-$4,.(/(1*.71*$1&(40,1!D2D>71>1>C1A1:1A1;6?;DB41>:1A9:1A9;5<5>7;D>71>35A=9>41@1C4931A945>71>@5AC?<?>71>$0%$4
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Gambar 6.14Letak dan sifat bayangan benda padacermin cekungGambar 6.13Hubungan antara fokus dan jari-jari cermin cekungPRFRfAO)))Keterangan:s= jarak benda ke cerminh= tinggi bendaf=jarak fokush' = tinggi bayangans'= jarak bayangan ke cermin 5>71>=5>77D>1;1>@5AB1=11>35A=9>C5AB52DC>4141@1C=5>5>CD;1>:1A1;21H1>71>B52D1825>41 41@D>@5A25B1A1>21H1>71>Konvensi tanda untuk pemantulan:Ks bernilai + jika objek berada didepan cermin (objek maya)bernilai – jika objek di belakangcermin (objek nyata)Ks’ bernilai + jika objek berada didepan cermin (objek nyata)bernilai – jika objek berada dibelakang cermin (objek maya)Kr, f bernilai + jika pusatkelengkungan berada di depancermin (cermin cekung)bernilai – jika pusat kelengkunganberada di belakang cermin(cermin cembung).IngatlahBAPEDFOfs'Rsh'h
115Cahaya dan Optika494569>9B9;1>B521719@5A21>49>71>1>C1A125B1AC9>77921H1>71>41>25B1AC9>77925>41 ,531A1=1C5=1C9B41@1C49CD<9B/ %
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#149@5A25B1A1>>H1;1<9B961C21H1>71>C571;=1H141>49@5A;539<3 Contoh 6.5Kata Kunci•optika geometri•optika fisis•pemantulan baur•pemantulan halus•bayangan nyata•bayangan maya•titik fokus utama•pusat kelengkunganTes Kompetensi Subbab B(4-$.$1/$+'$/$0%7.7/$6,+$1 ,525A;1BB9>1A41C1>7:1CD8@141B52D18@5A=D;11>35A=9>45>71>BD4DC J #9;1499>79>;1>B9>1A@1>CD<?<5835A=9>;54D1B5:1:1A45>71>B9>1A41C1>725A1@1;18BD4DC1>C1A135A=9>@5AC1=141>35A=9>;54D1
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117Cahaya dan OptikaC. Pembiasan Cahaya71A>41=5=181=9@5A9BC9F1@5=291B1>3181H1<1;D;1><18;5791C1>25A9;DC )5A81C9;1>>H1<1<1=@DB5>C5AB5@5AC9@141.6,8,6$5
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1791>@5>B9<H1>7C5A35<D@;519A;5<981C1>@1C18 )5A81C9;1>@D<1:9;149<9>7;D>71>>41C5A41@1C;?<1=H1>7:5A>9841B1A;?<1=C5AB52DCC5A<981C<529841>7;1< )5A9BC9F1C5AB52DC:D71=5AD@1;1>3?>C?8@5A9BC9F1@5=291B1>3181H1 Aktivitas Fisika 6.2Pembiasan dan PemantulanTujuan PercobaanMengamati peristiwa pembiasan dan pemantulan.Alat-Alat Percobaan1.Baterai kering 6.Kapas2.Pengunci kertas 7.Bohlam kecil dalam wadah3.Pensil 8.Klip kertas4.Obeng, gunting, dan double tape 9.Kabel5.Aluminium foil10.Botol air plastikLangkah-Langkah Percobaan 1.Potong bagian atas botol, kemudian menggunakan pensil lubangi botoldi pinggiran botol. 2.Rekatkan aluminium foil di dalam bagian atas botol yang sudah dipotong,seperti pada gambar (b). 3.Pasangkan dua buah kabel pada bohlam kecil yang sudah ditempatkanpada wadahnya. 4.Satukan baterai secara seri, lalu rekatkan kabel ketiga pada bagian bawahbaterai (kutub negatif ), seperti pada gambar (d). 5.Rekatkan satu kabel dari wadah bohlam ke bagian atas baterai (kutub positif ). 6.Masukkan kabel ke dalam lubang di pinggir botol, penuhi botol dengankapas dan tempatkan kedua kabel dengan pengunci kertas. 7.Tempatkan wadah bohlam di atas baterai, dan tempatkan tengah-tengahbohlam tepat di bagian atas botol yang sudah diratakan aluminium foil. 8.Bengkokkan klip kertas dan tempatkan pada salah satu ujung penguncikertas sehingga menjadi saklar senter tersebut. 9.Tekan ujung lainnya klip kertas ke pengunci kertas yang lain senter kini menyala.10.Apa yang menyebabkan nyala filamen lampu menyebar ke depan senter?11.Apa manfaat adanya aluminium foil pada bagian atas botol yangdipotong? Peristiwa apa yang terjadi pada aluminium foil tersebut?(a)(b)(c)(d)(e) ,52D1825>4149<5C1;;1>4945@1>35A=9>35=2D>7B545=9;91>AD@1B589>77125B1A21H1>71>>H1 ;1<9 #9;121H1>71>H1>7C5A25>CD;C5@1CL 41>:1A9:1A9;5<5>7;D>71>35A=9>35=2D>7
3=89CD>7:1A1;25>41;535A=9> Gambar 6.18Pensil seperti patah ketikatercelup ke dalam air
118Mudah dan Aktif Belajar Fisika untuk Kelas X1. Indeks Bias">45;B291B41@1C49@1>41>7B521719BD1CD;5=1=@D1>=549D==5=291B;1>=5=25<?;;1>1A18A1=21C3181H1 #9;13181H125A75A1;41A9E1;D=1C1DD41A1;5=549D=<19>9>45;B291B>H149B52DC&+!"(/ & /*10) (=549D=C5AB52DC )1415;B@5A9=5>,>5<<9DB>9<199>45;B291BH1>74941@1C+ =5AD@1;1>>9<199>45;B291B=DC<1;;131;1A5>13181H125A75A1;41A9E1;D=1C1DD41A1;5;131 ,531A1=1C5=1C9B41@1C49CD<9BB52171925A9;DC L+
22.Hukum Pembiasan)5=291B1>3181H1C941;B5=21A1>7C5C1@9=5>79;DC98D;D=8D;D=@5=291B1> !D;D=@5=291B1>@5AC1=1;1<949>H1C1;1>?<58#,//(%424'!1(//,7518<9 9B9;125A;521>7B11>5<1>41 !1(//,75=5<1;D;1>5;B@5A9=5>45>71>=5<5F1C;1>B525A;1BB9>1A@14121<?;;131 5A41B1A;1>81B9<5;B@5A9=5>H1>749<1;D;1>>H1!1(//,75;5=D491>=5>H1C1;1>!D;D=")5=291B1>>H1H19CD-". +!&+$ +/&+1//1!10! 0 +$! +/&+1//1!10 & /! .&/1 01 % 4 4 +$! 0 +$! .&/1 01*"!&1*("*"!&1*) &+*".1- ( +/1 01(,+/0 +0 4 +$ "/ .+4 / * !"+$ + -". +!&+$ + &+!"(/ & / ("!1 *"!&1* 0"./" 10+9B9>&+AB9>.B9>B9>.&+&.+"$%(/
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119Cahaya dan Optikamedium air(medium–1)medium kaca(medium–2)Gambar 6.20Sinar yang melalui dua mediumberbeda, yaitu air dan kaca.,531A1D=D=:9;13181H125A75A1;41A9=549D= ;5=549D=
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; =5=9<9;9=1;>169B9BH19CD;535@1C1>3181H141<1=BD1CD=549D=25A21>49>7C5A21<9;45>71>>9<199>45;B291B>H1 &1;BD4>H1:9;19>45;B291BB5=1;9>25B1A;535@1C1>3181H1B5=1;9>;539< ,5217193?>C?8;535@1C1>3181H141<1==549D=;131<5298;539<4921>49>7;1>45>71>;535@1C1>3181H1;5C9;1=5A1=21C41<1=19A <1B1>>H19>45;B291B=DC<1;;131<529825B1A41A9@1419>45;B=DC<1;19A ,5<19>9CD>41:D7141@1C=5>H9=@D<;1>218F1;5C9;175<?=21>7=5A1=21C41A9BD1CD=549D=;5=549D=<19>H1>79>45;B291B>H125A2541@1>:1>775<?=21>741>25B1A;535@1C1>275<?=21>7C5AB52DC25AD218>1=D>6A5;D5>B9#75<?=21>7C5AB52DCC941;25AD218 $5C5A1>71>+9>45;B291B=DC<1;=549D= +9>45;B291B=DC<1;=549D=
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3.Hubungan Cepat Rambat Cahaya dan Indeks Bias Medium)5A81C9;1>$0%$4
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H1>7<5298A1@1C ,5C5<18F1;CD075<?=21>72941>7)*25A141@1412941>7,+20202020 22Gambar 6.21Pembiasan cahaya melalui duamediummedium 1medium 2))RSPQ1221
120Mudah dan Aktif Belajar Fisika untuk Kelas X 1<1=B52D185;B@5A9=5>D>CD;=5>5>CD;1>;535@1C1>3181H14941<1=19AB5?A1>7B9BF1=5<5F1C;1>B525A;1B3181H1;541<1=19A45>71>BD4DC41C1>7 J $5=D491>B9BF1=5>31C1CBD4DC291BH1>7C5A:1494941<1=19AC5A>H1C125B1A>H1
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B Contoh 6.6Gambar 6.22Sinar datang dibiaskan:(a) mendekati garis normal jika n1 < n2;(b) menjauhi garis normal jika n1 > n2.in1n2rn1>n2irn1n2n1<n2,55;?A9;1>25A1414941B1A;?<1=H1>741<1=>H1=19A+B5@5AC9C1=@1;@14171=21A49B1=@9>7 )141;541<1=1>25A1@1;18<5C1;9;1>41B1A;?<1=C5AB52DCC5A<981C?<58@5>71=1C41A9@5A=D;11>19A:9;11 9;1>49<981C@5>71=1CB531A1C571;<DADB2 BD4DC1>C1A1=1C141>71A9B>?A=1<B525B1A J $9$%1 )5A81C9;1>71=21A #9;1@5>71=1C=5<981C9;1>B531A1C571;<DADB1;1>=5=5>D89@5AB1=11>C1>.B9>.41>C1>&B9>&,9>1A41C1>741A99;1>B589>771C1> B9>C1> B9>&&!..!1C1D1! &.+!+!=1;1;541<1=1>9;1>49@5A?<58H19CD
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= Contoh 6.7dasar kolam4 mnud = 1nair = 43rd = 4 mird 'i,521719;?>B5;D5>B941A9!D;D=",>5<<9DB9>9B9>1A41C1>741A9=549D=;DA1>7A1@1C;5=549D=<5298A1@1C+ +/&+ . ( +!& & /( +*"+!"( 0&$ .&/+,.* )! +'&( /&+ .! 0 +$! .&*"!&1*)" &%. - 0("*"!&1*(1. +$. - 0++B9>1A1;1>49291B;1>=5>:1D8971A9B>?A=1< (4+$6,.$1$0%$4
matapengamat(a)(b)
121Cahaya dan Optika4.Sudut Kritis dan Pemantulan Sempurna&5>71@125A<91>C1=@1;25A;9<1D1>;5C9;13181H1:1CD8@141@5A=D;11>>H1&5>71@1@141B11CC5A9;=1C181A9:1<1>A1H125A1B@1<C1=@1;B5@5AC9C5A75>1>719A)141;54D175:1<1 9B9;1C5AB52DC3181H1=5>71<1=9@5=1>CD<1>B531A1B5=@DA>1 1719=1>1@5=1>CD<1>B5=@DA>141@1CC5A:149)5A81C9;1>$0%$4
1=21AC5AB52DC=5>D>:D;;1>3181H125A75A1;41A9=549D=<5298A1@1C;131;5=549D=;DA1>7A1@1CD41A11C1D41A9=549D=25A9>45;B291B<529825B1A;5=549D=25A9>45;B291B<5298;539<B589>771B9>1A291B>H1=5>:1D8971A9B>?A=1< $5C9;1BD4DC41C1>7>?<BD4DC291B>H1:D71>?<B5@5AC949CD>:D;;1>?<58B9>1A $5=D491>@141B11CBD4DC41C1>749@5A25B1AB9>1A
B9>1A41>B9>1ABD4DC291B@D>25AC1=21825B1A1C1DB5=1;9>=5>:1D8971A9B>?A=1< )141B11C25B1ABD4DC41C1>7C5AC5>CDH1;>9B5@5AC9B9>1A3181H149291B;1> JC5A8141@71A9B>?A=1<B589>771B9>1A291B>H1B5:1:1A45>71>@5A=D;11>2941>721C1B=549D=;131D41A1 )141;51411>B5@5AC99>9BD4DC41C1>749B52DCBD4DC;A9C9B 5>71>;1C1<19>BD4DC;A9C9B141<18BD4DC41C1>7;5C9;1B9>1A41C1>749291B;1>B525B1A J #9;1BD4DC41C1>749@5A25B1A<179=5<52989BD4DC;A9C9B3181H1C941;1;1>49291B;1>=5<19>;1>49@1>CD<;1>B531A1B5=@DA>1 AC9>H13181H1C941;1;1>;5<D1A41A9=549D=;131B5@5AC949CD>:D;;1>?<58B9>1A )5A9BC9F19>9<18H1>749B52DC@5=1>CD<1>B5=@DA>15A41B1A;1>81<C5AB52DC41@1C49B9=@D<;1>218F1@5=1>CD<1>B5=@DA>181>H1C5A:149:9;1=5=5>D894D1BH1A1C25A9;DC 1 181H141C1>741A9=549D=<5298A1@1C;5=549D=;DA1>7A1@1C 2 ,D4DC41C1>7<529825B1A41A9@141BD4DC;A9C9B Gambar 6.23Deskripsi geometri tentang sudut kritisdan pemantulan sempurnan2n1(n1>n2)123456iudarakacaiiirrrrirAktivitas Fisika 6.3Sepotong plastik transparanterapung dipermukaan air. Agarsinar datang seperti pada gambardi atas dipantulkan sempurna olehpermukaan batas plastik air. Jikaindek bias plastik nk dan indek biasair na, berapa besar sudut?Tantanganuntuk AndaudaraairplastikPemantulan SempurnaTujuan PercobaanMengamati pemantulan sempurna.Alat-Alat PercobaanGelas minum, lilin, dan air.Langkah-Langkah Percobaan1.Isilah gelas minum dengan air sampai hampir penuh.2.Letakkan gelas tersebut di pinggir meja.3.Nyalakan lilin pendek dan letakkan dekatdengan gelas.4.Perhatikan gambar berikut.Amati dari arah yang berseberangandengan lilin dari arah agak dibawah permukaan.5.Apa yang dapat Anda amati?6.Apa kesimpulan Anda dari kegiatan ini?)A9>B9@@5=1>CD<1>B5=@DA>149=1>611C;1>41<1=C5;>?<?79;?=D>9;1B9H1;>9@141B5A1C?@C9;#& ". ,-0& B5@5AC9@141$0%$4
,5A1C?@C9;141<18BD1CDB5A1C81<DBC5A2D1C41A9@<1BC9;1C1D;131H1>7497D>1;1>D>CD;=5>H1<DA;1>3181H11C1D75<?=21>75<5;CA?=17>5C9; ,5A1C?@C9;C5A49A91C1B21791>9>C941>21791><D1AB521719@5=2D>7;DB>H1 1791>9>C9C5A2D1C41A9;131H1>7=5=9<9;99>45;B291BC9>77941>25A;D1<9C1B219; matapengamat
122Mudah dan Aktif Belajar Fisika untuk Kelas XGambar 6.24(a) Pemantulan sempurnapada serat optik.(b) serat optik.(a)(b)Contoh 6.8!9CD>7BD4DC;A9C9B25A<91>H1>7=5=9<9;99>45;B291B=DC<1;
@141B11C49<5C1;;1>49D41A1 $9$% 9;5C18D9+ +
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+L $5C5A1>71>&;BD4DC;A9C9B(11sintir5Pembiasan pada Kaca Plan Paralel$131@<1>@1A1<5<141<18B5;5@9>7;131H1>7;54D1B9B9@1>:1>7>H1492D1CB5:1:1A $131@<1>@1A1<5<41@1C497D>1;1>D>CD;=5>71=1C9:1<1>>H1B9>1AH1>7=5>71<1=9@5=291B1>41>D>CD;=5>5>CD;1>9>45;B291B;131C5AB52DC ,9>1A41C1>741A9D41A1=5<5F1<9;131B5C521<!3=;5=D491>=5>D:D=549D=D41A1;5=21<9 )141@A?B5BC5AB52DCB5@5AC9C1=@1;@141$0%$4
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L ">45;B291BH1>7C9>7791;1>=5>71;921C;1>BD4DC;A9C9B;539<B589>771B9>1A41C1>745>71>BD4DC41C1>7H1>7C941;C5A<1<D25B1A1;1>=5>71<1=9@5=1>CD<1>B5=@DA>1 1791><D1AH1>7=5AD@1;1>@5=2D>7;DBC5A2D1C41A9@<1BC9;1C1D=1C5A91<<19>H1>725A6D>7B9=5<9>4D>7921791>9>C9 (<58;1A5>13181H11C1D75<?=21>75<5;CA?=17>5C9;H1>7=1BD;;541<1=B5A1C?@C9;=5>71<1=9@5=1>CD<1>B5=@DA>1@141B11C;5<D1A41A9B5A1C?@C9;5>5A793181H1C941;21>H1;H1>789<1>7 5A41B1A;1>81<9CD:9;1H1>749;9A9=141<18B9>H1<B9>H1<;?=D>9;1B941<1=25>CD;75<?=21>73181H1@141B11C49C5A9=149C5=@1CCD:D1>B9>H1<C5AB52DCB1=@19B531A1DCD8C1>@121>H1;;589<1>71>5>5A79 5A41B1A;1>@141@A?B5BC5A:149>H1@5=1>CD<1>B5=@DA>141@1C49C5>CD;1>@D<125B1A>H1BD4DC;A9C9BD>CD;4D1=549D=C5AC5>CDB52171925A9;DC )141B11CC5A:149@5=1>CD<1>B5=@DA>125A<1;D@5AB1=11>25A9;DC Gambar 6.25Seberkas cahaya memasukikaca plan paraleldDBAOtr2r1i1Gambar 6.26Pergeseran arah sinarpada kaca plan paralelB9>B9>+&.+45>71>++41>. JB589>771
123Cahaya dan Optika(1cosdrL 5A41B1A;1>( 49@5A?<58( 3?B ( (!.5A41B1A;1> (45$0$$1
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JC5>CD;1>25B1A@5A75B5A1>H1>7491<1=9?<58B9>1A<1B5AC5AB52DC $9$% 9;5C18D90J.
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181H141C1>741A9D41A1=5>D:D2941>7@5A=D;11>@A9B=11;1>49291B;1>=5>45;1C971A9B>?A=1< $5=D491>;5C9;13181H1=5>9>771<;1>@A9B=1=5>D:DD41A13181H1C5AB52DC1;1>49291B;1>=5>:1D8971A9B>?A=1< ,5C5<18=5<5F1C9@A9B=13181H1=5>71<1=945E91B9 5B1A>H1BD4DC45E91B9H1>7491<1=93181H1141<18B52171925A9;DC )5A81C9;1>$0%$4
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6 6 )5A81C9;1> J.1 J.2Gambar 6.27Prisma segitigaGambar 6.28Jalannya sinar pada prismaNNsinardatangsinarbias)
124Mudah dan Aktif Belajar Fisika untuk Kelas X J
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=549D=;131+ =549D=D41A1 J,D4DC45E91B94989CD>745>71>=5>77D>1;1>@5AB1=11> 12ir(<58;1A5>1&41>C5<1849;5C18D9>9<19.BD4DC291B;54D1@5A<D4931A9C5A<5298418D<D )141@5A=D;11>@5=291B@5AC1=125A<1;D@5AB1=11>,>5<<9DB25A9;DC Contoh 6.10Gambar 6.29Penurunan rumus sudut deviasiprisma7.Deviasi Minimum,5C91@B9>1AH1>741C1>7@141@A9B=11;1>=5>71<1=945E91B9H1>7=5>781B9<;1>BD4DC45E91B9C5AC5>CD ,1<18B1CDB9>1A41C1>7C5AC5>CD@1BC91;1>=5>781B9<;1>>9<19BD4DC45E91B9=9>9=D= $1@1>;?>49B9;8DBDBB9>B9>&+.+45>71>++D41A141>+
;131B9> B9>B9> ... '9<19&49C5>CD;1>B52171925A9;DC 211irr260 19,47 40,53i $5=D491>>9<19.49C5>CD;1>B52171925A9;DC B9> B9>B9> B9> J+.&..+B9> 1A3B9> J...#149BD4DC45E91B9H1>7491<1=93181H1;5C9;1=5<5F1C9@A9B=1;131C5AB52DCB525B1A
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125Cahaya dan Optika7<7A3?8/273?2/@/?9/<6/@7:>3;0B9A7/<# "2/>/AA3?8/27>/2/@//A@B2BA2/A/<5>3?A/;/@/;/23<5/<@B2BA07/@932B/ 3@/?<E/@B2BA23C7/@7;7<7;B;@30B/6>?7@;/2/>/A271/?7@30/5/703?79BA':369/?3</ ;/9/ @367<55/ K &7:/7 27;/@B99/<932/:/; %12!-!!. 7@367<55/23C7/@7>?7@;/;3<8/27K
3?2/@/?9/< B9B;*<3::7B@ @7<@7< K %12!-!!. 72/< %12!-!!. 727@B0@A7AB@79/<932/:/; %12!-!!. 7@367<55/27>3?=:36 @7<@7<@7<@7< "79/9317:@7< @367<55/KK K K K *30B/6>?7@;/E/<5A3?0B/A2/?79/1/ E/<5;3;7:797@B2BA>3;07/@
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;3;/@B97>?7@;/03?/>/9/6@B2BA23C7/@7;7<7;B;>?7@;/A3?@30BA!5!" 793A/6B7
I
;327B;/7? ;327B;9/1/K #3A3?/<5/<@B2BA23C7/@7;7<7;B;1,2n@B2BA07/@?3:/A74;327B; A3?6/2/>;327B; @B2BA23C7/@7>?7@;/Contoh 6.11
126Mudah dan Aktif Belajar Fisika untuk Kelas X8.Lensa$3<@/A3:/62793</:=?/<5@38/92/6B:B(/2//0/2>3?A3<5/6/<=?/<5=?/<5.B</<72/<?/0@B2/6;3<53</:2/<;3<55B</9/<:3<@/*//A7<7:3<@/8B5/0/<E/9275B</9/<@30/5/70/57/<BA/;//:/A/:/A@3>3?A79/;3?/A3?=>=<5;79?=@9=>>?=E39A=?2/<9/1/;/A/*3;B//:/AA3?@30BA@/<5/A>3<A7<52/<03?5B</2/:/;93672B>/<':369/?3</7AB;3;/6/;7@74/A@74/A>3;07/@/<>/2/:3<@/@/<5/A>3<A7<5$3<@//2/:/603<2/03<7<5E/<5270/A/@7=:362B/>3?;B9//<:3<59B<5(3?;B9//<;3:3<59B<5A3?@30BA;3?B>/9/<0/57/<>3?;B9//<0=:/$3<@/E/<523;797/<27@30BA:3<@/@43?7@(3?;B9//<:3<@/@43?7@2/>/A03?B>/932B/<E/13;0B<5932B/<E/139B<5/A/B5/0B<5/<13;0B<52/<139B<5$3<@/@43?7@A3?27?7/A/@2B/83<7@E/7AB:3<@/13;0B<52/<:3<@/139B<5$3<@/13;0B<59=<C39@/A/B:3<@/9=<C3?53</2/:/6:3<@/E/<50/57/<A3<5/6<E/:3076A30/:2/?7>/2/0/57/<A3>7<E/$3<@/7<703?@74/A;3<5B;>B:9/<03?9/@@7</?!-"!1 2/>B<:3<@/139B<59=<9/4/A/B:3<@/27C3?53</2/:/6:3<@/E/<50/57/<A3<5/6<E/:3076A7>7@2/?7>/2/0/57/<A3>7<E/$3<@/7<703?@74/A;3<E30/?9/<03?9/@@7</?!-"!1 *303:B;:30768/B6;3;/6/;743<=;3</43<=;3</E/<5A3?8/27>/2/:3<@/<2/6/?B@;3<53A/6B70/57/<0/57/<:3<@/23<5/<0/79(/2/:3<@/A3?2/>/A>B@/A=>A79A7A794=9B@2/<>B@/A93:3<59B<5/<:3<@/!-"!1 ;3;>3?:76/A9/<@93;/@30B/6:3<@/2/<0/57/<0/57/<<E/a.Pembiasan Cahaya pada Lensa Cembung /6/E/E/<58/AB6>/2/>3?;B9//<:3<@/13;0B<5/9/<;3<5/:/;7>3;07/@/<3?9/@03?9/@@7</?2/A/<5/9/<2707/@9/<@367<55/03?9/@03?9/@@7</?07/@<E/;3<5B;>B:(3?6/A79/<!-"!1 /57/<:3<@/E/<5A30/:/9/<;3<56/;0/A1/6/E/:30760/<E/92/?7>/2/0/57/<:3<@/E/<5A7>7@':369/?3</13>/A?/;0/A1/6/E/272/:/;:3<@/:30769317:2/?7>/2/27B2/?/03?9/@03?9/@@7</?07/@/9/<;3<5B;>B:!AB:/6@30/0<E/:3<@/13;0B<503?@74/A9=<C3?53< ).!12).!1)23)-%5!0!$!,%.2!#%-"4.'/E/<5/<03<2/=:36:3<@/13;0B<52/>/A2703<AB923<5/<1/?/;3<55/;0/?9/<@7</?@7</?7@A7;3D/<E/*7</?@7</?7@A7;3D/>/2/:3<@/13;0B<5/2/A75/0B/6E/7AB@30/5/703?79BA/ *7</?E/<52/A/<5@38/8/?@B;0BBA/;/2707/@9/<;3:/:B7A7A794=9B@/9A74:3<@/0 *7</?E/<52/A/<5E/<5;3:/:B7A7A794=9B@>/@742707/@9/<@38/8/?@B;0BBA/;/1 *7</?E/<52/A/<5;3:/:B7>B@/A=>A79A72/9;3<5/:/;7>3;07/@/<Gambar 6.30Lensa cembung bersifat konvergen(mengumpulkan cahaya)Gambar 6.31Lensa cekung bersifat divergen(menyebarkan cahaya)Gambar 6.32Bagian-bagian lensa cembung danlensa cekung(3<3<AB/<@B2BA23C7/@7;7<7;B;;3<55B</9/<>3?@/;//<= K K
I=
K
IIKeterangan:O= pusat optikOF1= jarak fokus dari pusat optikOP1= jari-jari kelengkungan lensaF1 dan F2= titik fokusP1 dan P2= pusat kelengkungan lensaGambar 6.33Sinar-sinar istimewa pada lensacembungF1F1F1F2F2F2(a)(b)(c)F2F1P2POF2F1PP1O
127Cahaya dan OptikaF2F1ABOruangbendaI I IruangbendaI IruangbendaIruangbendaIVruangbayangan(IV )ruangbayangan(I)ruangbayangan(III)ruangbayangan(II)Gambar 6.34Penamaan ruang pada lensacembung !.'+!(0%-"%.34+!."!6!.'!.0!$!,%.2!#%-"4.',<AB9;3;>3?;B2/6>3;03<AB9/<0/E/<5/<?B/<52723>/<2/<2703:/9/<5:3<@/270/57;3<8/270303?/>/?B/<5/<@3>3?A7>/2/!-"!1
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b.Pembiasan Cahaya pada Lensa Cekung3?032/23<5/<:3<@/13;0B<5:3<@/139B<503?@74/A;3<E30/?9/<03?9/@@7</?3?9/@@7</?E/<58/AB6>/2/>3?;B9//<:3<@/139B<5/9/<2707/@9/<@31/?/;3<E30/? ).!12).!1)23)-%5!0!$!,%.2!#%+4.'(/2/:3<@/139B<58B5/A3?2/>/A@7</?@7</?7@A7;3D/E/<503?5B</0/57>3;03<AB9/<0/E/<5/<*7</?@7</?7@A7;3D/>/2/:3<@/139B<5/2/:/6@30/5/703?79BA!-"!1 / *7</?E/<52/A/<5@38/8/?@B;0BBA/;/2707/@9/<@3/9/</9/<03?/@/:2/?7A7A794=9B@0 *7</?E/<52/A/<5;3<B8BA7A794=9B@2707/@9/<@38/8/?@B;0BBA/;/1 *7</?E/<52/A/<5;3:/:B7>B@/A=>A7927A3?B@9/<A72/9;3<5/:/;7>3;07/@/<!.'+!(0%-"%.34+!."!6!.'!.0!$!,%.2!#%+4.'(3?6/A79/<!-"!1
,<AB9;3<55/;0/?9/<0/E/<5/<03<2/E/<5276/@7:9/<=:36:3<@/139B<527:/9B9/<1/?/@30/5/703?79BA/ 7:B97@2B/0B/6@7</?7@A7;3D/:3<@/139B<50 *7</?@3:/:B2/A/<52/?7>3?;B9//<:3<@/2/<2707/@9/<9303:/9/<5:3<@/1 3<2/E/<527:3A/99/<2723>/<:3<@/139B<5@3:/:B;3<56/@7:/<0/E/<5/<E/<5;3;7:797@74/A;/E/A35/927>3?9317:2/<A3?:3A/92723>/<:3<@/139B<5Gambar 6.36Sinar-sinar istimewa pada lensacekungF1F2F1F2F1F2000Gambar 6.35Pembentukan bayangan oleh lensacembungGambar 6.37Pembentukan bayangan oleh lensacekung(a)(b)(c)F2F1AOBA’B’s’fshh’
128Mudah dan Aktif Belajar Fisika untuk Kelas XK
*30B/6:3<@/A7>7@;3;7:7977<239@07/@ 270/A/@7=:36 >3?;B9//<13;0B<52/<139B<5A7>3/27:3A/99/<27B2/?/"/?78/?7:3<59B<5932B/>3?;B9//<03?AB?BAAB?BA
1;2/<
1; 7AB<58/?/94=9B@:3<@/A7>7@A3?@30BA!5!" 793A/6B7
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1;"/278/?/94=9B@:3<@/
1;Contoh 6.12 Gambar 6.38Lensa tipis(a) bikonveks, R1 > 0 ; R2 < 0(b) konvek konkaf, R1 > 0 ; R2 > 0(c) plan konveks, R1 = ; R2 < 0(d) bikonkaf, R1 < 0 ; R2 > 0(e) konkaf konveks, R1 < 0 ; R2 < 0(f ) plan konkaf, R1 = ; R2 > 0 %.2!3)0)2$3<@/A7>7@/2/:/6:3<@/E/<5;3;7:79793A30/:/<8/B6:30769317:270/<27<59/<23<5/<27/;3A3?93:3<59B<5/<<E/$3<@/A7>7@2/>/A27:/;0/<59/<23<5/<@30B/65/?7@(/2/!-"!1 27AB<8B99/<0303?/>/83<7@:3<@/A7>7@ /:/;:3<@/A7>7@03?:/9B>3?@/;//<03?79BAK (b)(a)(c)R1R1R2R2(e)(d)(f )R1R2R1R2R1R2R1R2c.Perbesaran Bayangan Lensa(3<53?A7/<>3?03@/?/<0/E/<5/<>/2/:3<@/@/;/23<5/<>3<53?A7/<>3?03@/?/<0/E/<5/<>/2/13?;7<:3<59B<5(3?03@/?/<0/E/<5/<272347<7@79/<@30/5/7>3?0/<27<5/</<A/?/A7<5570/E/<5/<2/<A7<55703<2//A/B8/?/90/E/<5/<A3?6/2/>:3<@/2/<8/?/903<2/93:3<@/*31/?/;/A3;/A7@2/>/A27AB:7@/A/B' K #3A3?/<5/<>3?03@/?/<0/E/<5/< 8/?/90/E/<5/<93:3<@/A7<5570/E/<5/<8/?/903<2/93:3<@/A7<55703<2/"79/>=@7A7403?/?A70/E/<5/<03?@74/A;/E/2/<A35/9"79/K<35/A7403?/?A70/E/<5/<03?@74/A<E/A/2/<A3?0/:79*30B/603<2/03?27?7A35/9
1;2723>/<:3<@/A7>7@9=<C3?53<E/<58/?/94=9B@<E/ 1;+3<AB9/</ :3A/90/E/<5/<0 >3?03@/?/<0/E/<5/<1 @74/A0/E/<5/<Contoh 6.13Tugas Anda 6.1Perhatikan kembali gambarpembentukan pada lensacembung dan lensa cekung.Temukan oleh Anda sehinggadiperoleh Persamaan (6–24).Konvensi tanda untuk pembentukanbayangan oleh lensa:Js bernilai + (Objek nyata) untukbenda-benda di depan permukaan(sisi datang);bernilai – (Objek maya)untukbenda-benda di belakangpermukaan (sisi transmisi);Js’ bernilai + (Bayangan nyata)untuk bayangan-bayangan didepan permukaan (sisi transmisi);bernilai – (Bayangan maya) untukbayangan-bayangan di depanpermukaan (sisi datang);Jr, f bernilai + jika pusatkelengkungan berada pada sisitransmisi;bernilai – jika pusat kelengkunganberada pada sisi datang.Ingatlah
129Cahaya dan Optika!5!" 793A/6B7
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1; K A/<2/<35/A74;3<B<8B99/<0/E/<5/<<E/A/2/<A3?0/:79"/27>3?03@/?/<0/E/<5/<<E/ 1 *74/A0/E/<5/<J <E/A/2/<A3?0/:7903?2/@/?9/<<7:/7 K<35/A74J @/;/03@/?23<5/<03<2/<E/03?2/@/?9/<<7:/7 InformasiSebuah lensa Fresnel adalah lensaplan-konveks yang tebal dibentukberlipat-lipat agar diperoleh lensadatar yang memiliki sifat optiknya,namun lebih tipis sehingga memilikikehilangan penyerapan yang lebihsedikit. Lensa Fresnel biasanya tipisdan lentur, ukurannya sekitar 0,015inch (0,38 mm) dengan alur lekukanpada satu permukaan.Salah satu penerapan lensaFresnel adalah untuk alatpemfokusan sensor inframerah.Lensa Fresnel dapatmemperpanjang rentangpendeteksian mencapai 100 kaki.A Fresnel lens is a plano convex lensthat has been collapsed on it self toform a flat lens that retains its opticalcharacteristics but is much thinnerand therefore has less absorption loss.A Fresnel lens is ussually thin andflexible and is about 0,015 inch (0,38mm) thick with grooves molded onone surface.One of an application of Fresnellens is to focusing devices forinfrared sensors. A Fresnel lens canextend detection range to about100 feet.Sumber: www.glolab.comlensa Fresnelinframerahuntuk AndaInformation for Youd.Kekuatan Lensa"/?/94=9B@@30B/6:3<@/@/<5/A>3<A7<5/?A7<E/9/?3</2/>/A;3<E/A/9/<B9B?/<939B/A/<:3<@/#39B/A/<@30B/6:3<@/@/<5/A03?5/<AB<5>/2/<7:/78/?/94=9B@:3<@/A3?@30BA#39B/A/<:3<@/@7;0=:272347<7@79/<@30/5/793;/;>B/<;3<5B;>B:9/</A/B;3;/<1/?9/<03?9/@1/6/E/3@/?<E/939B/A/<:3<@/03?0/<27<5A3?0/:7923<5/<8/?/94=9B@<E/"79/8/?/94=9B@<E/03@/?939B/A/<:3<@/9317:*30/:79<E/879/8/?/94=9B@:3<@/9317:939B/A/<:3<@/03@/?*31/?/;/A3;/A7@>3?<E/A//<A3?@30BA27AB:7@K #3A3?/<5/<939B/A/<:3<@/27=>A?78/?/94=9B@;3A3?*/AB/<2/:/;27=>A?7879/8/?/94=9B@:3<@/27<E/A/9/<2/:/;;3A3?,<AB9:3<@/13;0B<5<7:/7(@3:/:B03?<7:/7>=@7A749/?3</<7:/7>=@7A74*30/:79<E/B<AB9:3<@/139B<5<7:/7
<35/A74K9/?3</<7:/78/?/94=9B@:3<@/139B<5<35/A74K*30B/6:3<@/9=<C3?53<;3;7:7978/?/94=9B@ 1;3?/>/9/6939B/A/<:3<@/A3?@30BA!5!" 793A/6B7 1;:3<@/9=<C3?53</A/B13;0B<53?2/@/?9/<>3?@/;//<
;3A3?27=>A?7"/27939B/A/<:3<@/27=>A?7Contoh 6.14
130Mudah dan Aktif Belajar Fisika untuk Kelas Xe.Susunan Dua Lensa:/A/:/A=>A79@3>3?A7;79?=@9=>2/<A3?=>=<5;3<55B</9/<2B/0B/6:3<@//A/B:3076/E/<5/</967?E/<5A3?03<AB9;3?B>/9/<6/@7:2/?7>?=@3@>3;07/@/<=:36932B/:3<@/A3?@30BA%B:/;B:/1/6/E/2/?703<2/1/6/E/>/<AB:/<2707/@9/<=:36:3<@/>3?A/;/@367<55/A3?03<AB90/E/<5/<!/E/<5/<!7<793;B27/<@3=:/6=:/6;3?B>/9/<03<2/0/57:3<@/932B//E/<5/<!!/A/B0/E/<5/<A3?/967?A3?03<AB9=:36:3<@/932B/ /?/;3<3<AB9/<0/E/<5/<0/7923<5/<1/?/5/;0/?;/B>B<1/?/>3?67AB<5/<A3A/>;3<579BA793A3<AB/<E/<5A3:/6270/6/@@303:B;<E/3?2/@/?9/<!-"!1 A3?@30BA2/<9/?3<//<A/?932B/:3<@/;3;7:7978/?/9A3?A3<AB@7;0=:;/9/A3?2/>/A6B0B<5/<@30/5/703?79BAGambar 6.39Pembentukan bayangan oleh duabuah lensa cembungTes Kompetensi Subbab C%1*!+!.,!($!,!-"4+4,!3)(!. +=5/?@32/<5;3:/9B9/<39@>3?7;3<B<AB9;3<3<AB9/<9313>/A/<1/6/E/272/:/;0/6/<9/1/A30/:!/;3:3>/@9/<@303?9/@1/6/E/>/2/>3?;B9//<9/1/A30/:23<5/<@B2BA
I+3?<E/A/03?03:=9272/:/;9/1/23<5/<03@/?>3;03:=9/<A3?6/2/>5/?7@<=?;/:
I"79/9313>/A/<1/6/E/27B2/?/
; @03?/>/9/613>/A?/;0/A1/6/E/272/:/;9/1/A30/:A3?@30BA "79/7<239@07/@;BA:/9/7?2/<7<239@07/@;BA:/9/:9=6=:
A3<AB9/</ 7<239@07/@/7??3:/A74A3?6/2/>/:9=6=:0 7<239@07/@/:9=6=:?3:/A74A3?6/2/>/7? 2/9/66B0B<5/</<A/?/<7:/77<239@07/@2/<93?/>/A/<;/@@/@B/AB03<2/ *30B/603<2/03?27?7A35/92723>/<:3<@/139B<5E/<5;3;7:7978/?/94=9B@
1;$B97@:/60/E/<5/<03<2/E/<52703<AB9=:3613?;7<139B<5A3?@30BA879// 03<2/A3?:3A/91;2723>/<:3<@/139B<50 03<2/A3?:3A/9 1;2723>/<:3<@/139B<51 03<2/A3?:3A/9
1;2723>/<:3<@/139B<5 B/0B/6:3<@/13;0B<527@B@B<@323;797/<?B>/@367<55/@B;0BBA/;/03?7;>7A$3<@/>3?A/;/;3;7:7978/?/94=9B@ 1;2/<8/?/94=9B@:3<@/932B/
1;*30B/603<2/E/<5A7<557<E/1;03?27?7A35/92723>/<:3<@/>3?A/;/>/2/8/?/9
1;+3<AB9/</ 5/;0/?>3;03<AB9/<0/E/<5/</967?0 :3A/90/E/<5/</967?1 A7<5570/E/<5/</967?2/<@74/A0/E/<5/</967?2 >3?03@/?/<A=A/:Kata Kunci•pembiasan (refraksi)•indeks bias•sudut datang•sudut bias•sudut kritis•kaca plan paralel•prisma•deviasi minimum•lensa sferis!!!
#3A3?/<5/<8/?/9/<A/?:3<@/ !8/?/90/E/<5/<:3<@/!!!8/?/903<2/:3<@/!!K D. Alat-Alat Optik(3<53A/6B/<;/<B@7/;3<53</7=>A79A3:/6;3:/67?9/<723723270B/A<E//:/A/:/A=>A79:/A/:/A=>A7927@30BA8B5/@30/5/7>3?/:/A/<E/<5;3;/<4//A9/<@74/A@74/A0/6/<93A79/2793</71/6/E//6/<0/6/<7<7;3<8/277@A7;3D/9/?3</03<AB9<E/F2F1F1F2bayanganpertama (I)bayanganakhir (II)lensa II(+)lensa I(+)bendasIs'Is'iIIs'IIL
131Cahaya dan OptikaGambar 6.40Bagian-bagian matafoveapangkalsaraf optikretinasklerairiskorneapupilcairandi sekitar mataotot siliarlensa1.Mata(3?</69/<<2/;3;0/E/<59/<0/5/7;/</879/;/<B@7/A72/927:3<59/>723<5/<;/A/>/E/<5<2/?/@/9/<93A79/<2/;3;38/;9/<;/A/B<AB90303?/>/@//A#37<2/6/<2/<67?B9>79B993672B>/<?/@/<E/A72/90357AB03?/?A7/<2/79/A/+B6/<./<5%/6/9B/@/A72/9;3<5/?B<7/9/<;/A/93>/2/<2//5/7;/</>?7<@7>93?8/;/A/93A79/;3:76/A@30B/6=0839(3?6/A79/<:/60/5/<;/A/>/2/!-"!1
(/2/D/9AB;/A/;3:76/A=0839:3<@/;/A//A/B:3<@/9?7@A/:7<;3;03<AB90/E/<5/<03<2/>/2/?3A7</E/<503?/2/270/57/<03:/9/<5;/A/)3A7</7<7276B0B<59/<=:36@/?/4@/?/4>3<5:76/A/<93=A/9@367<55/A7;0B:93@/<;3:76/A03<2//A/B=0839$3<@/;/A/;3?B>/9/<:3<@/E/<5A30/:A7>7@<E/2/>/A03?B0/6@3@B/723<5/<:3A/903<2/E/<5@32/<5;3<8/27=0839>3<5:76/A/<(3?B0/6/<A30/:A7>7@<E/:3<@/;/A/7<7;3<5B0/68/?/94=9B@:3<@/;/A/ 3<5/<1/?/7<7:3A/90/E/<5/<03<2/E/<5@32/<5;3<8/27>3?6/A7/</9/<@3:/:B8/AB6A3>/A27?3A7</@367<55/0/E/<5/<<E/A/2/?703<2/2/>/A27A3?7;/23<5/<83:/@879/0/E/<5/<A3?@30BAA3>/A8/AB627?3A7</"/?/9?3A7</23<5/<:3<@//2/:/6A3A/>*3;3<A/?/7AB@3A7/>03<2/E/<5;3<8/27>3?6/A7/<;3;7:7978/?/9E/<5A72/9@/;/A3?6/2/>:3<@/;/A/2/03<2/E/<5239/A@32/<52/<8/B60/69/<8/B6@39/:73<2/03<2/A3?@30BA2/>/AA3?:76/A879/0/E/<5/<03<2/<E/A3>/A8/AB627?3A7</':369/?3</7AB@/AB@/AB<E/1/?/E/<5;B<597</2/:/623<5/<>3?B0/6/<8/?/94=9B@:3<@/;/A/"/27>3?B0/6/<:3<@/;/A/@3@B<55B6<E/B<AB9;3<2/>/A9/<0/E/<5/<<E/A/27?3A7</a.Daya Akomodasi#3;/;>B/<:3<@/;/A/B<AB9;3<5B0/68/?/94=9B@<E/27@30BA& (/2/@//A;/A/;3:76/A03<2/E/<5239/A=A=A=A=A@7:7/?;3<35/<5@367<55/:3<@/;/A/:307613;0B<5*30/:79<E/>/2/@//A;3:76/A03<2/E/<58/B6=A=A=A=A@7:7/?;3<53<2B??7:39@@367<55/:3<@/;/A/:3076>7>76(/2/93/2//<<=?;/:=A=A=A=A@7:7/?03?/2/2/:/;93/2//<?7:39@</;B<@3<27>3<579/A2/:/;93/2//<A35/<5(/2/93/2//<7<703<AB9:3<@/;/A//5/92/A/?(/2/93/2//<7<7;/A/2/:/;93/2//<A72/903?/9=;=2/@7"79/03<2/E/<58/B6A/967<55/27239/A9/<=A=A=A=A@7:7/?/9/<;3<8/27A35/<5'A=A@7:7/?/9/<03?A/;0/6A35/<5879/03<2/@3;/97<239/A(/2/93/2//<7<7;/A/2/:/;93/2//<@32/<503?/9=;=2/@7"79/;/A/A3?B@03?/9=;=2/@7;/A/A3?/@/:3:/69/?3</=A=A@7:7/?A3?B@;3<35/<5b.Titik Dekat dan Titik Jauh3<2/6/<E/2/>/AA3?:76/A23<5/<83:/@879/A3?:3A/9272/3?/6>3<5:76/A/<;/A/ /3?/6>3<5:76/A/<;/A/7<703?/2/27/<A/?/A7A79239/A;/A//A/B " !" %"2/<A7A798/B6/A/B " !" !"
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03?79BAGambar 6.42Daerah penglihatanGambar 6.41Gambaran daya akomodasi matalensa lebih cembungbayangandifokuskan padaretinalensa lebih pipihbenda dekatbenda jauh(a)(b)PP = 25 cmPR = ~jangkauan penglihatan
132Mudah dan Aktif Belajar Fisika untuk Kelas Xc.Cacat Mata dan Penanggulangannya(/2/93<E/A//<<E/;/A/;/<B@7/A72/9@3;B/<E/<=?;/:#3A72/9<=?;/:/<;/A/;/<B@7/@3?7<527@30BA1/1/A;/A//A/B/03?/@7(/2/B;B;<E/;/@/:/61/1/A;/A/A3?8/279/?3</0/E/<5/<03<2/A72/9A3>/A8/AB627?3A7</2/E/<5;3<5/:/;71/1/A;/A/9/?3</0/E/<5/<03<2/8/AB62723>/<?3A7</2/</2/>B:/E/<58/AB62703:/9/<5?3A7</ /1/A;/A/2/>/A27A/<55B:/<5723<5/<;3<55B</9/<9/1/;/A/:3<@/9=<A/9/A/B=>3?/@7;/A/%/A/<=?;/:/A/B3;3A?=>7/2/:/6;/A/E/<5;3;7:79793;/;>B/<;3:76/A03<2/>/2/2/3?/6>3<5:76/A/<<=?;/:E/7AB/<A/?/A7A79239/A 1;2/<A7A798/B6A/967<55/3?79BA7<70303?/>/83<7@1/1/A;/A/E/<5@3?7<527/:/;7=:36;/<B@7/ )/0) !"4.!4(%/A/E/<5;3<5/:/;71/1/A;7=>7E/7AB;/A/E/<5;3;7:797A7A79239/A@/;/23<5/< 1; 1;2/<;3;7:797A7A798/B6A3?A3<AB
(3<23?7A/1/1/A;/A/7<7A72/92/>/A;3:76/A03<2/E/<58/B6@30/0:3<@/;/A/;7=>7;3<13;0B<52/<A72/92/>/A;3<8/27>7>76@30/5/7;/</;/A/<=?;/:970/A<E/0/E/<5/<03<2/8/B6@3:/:B8/AB62723>/<?3A7</,<AB9;3</<55B:/<571/1/A;/A/;7=>76/?B@27B>/E/9/</5/?0/E/<5/<A3>/A8/AB627?3A7</3?/?A7@303:B;@7</?2/A/<58/AB6>/2/:3<@/;/A/A3?:30762/6B:B@7</?2/A/<57<76/?B@27@30/?9/<':369/?3</7AB6/?B@270/<AB=:36:3<@/139B<5:3<@/27C3?53<E/<5939B/A/<:3<@/<E/@323;797/<?B>/@367<55/;/;>B;3;03<AB90/E/<5/<03<2/A3>/A8/AB6"79/:3<@/;/A/27/<55/>@43?7@0=:/23<5/<8/?/9>3?;B9//<23>/<:3<@/23<5/<?3A7</
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27=>A?7Contoh 6.15Gambar 6.43(a) Pada cacat mata miopi, bayanganbenda selalu jatuh di depanretina.(b) Cacat mata miopi diatasi denganmenggunakan lensa cekung.sinar-sinarsejajar daribenda jauhlensa cekung(a)(b)
133Cahaya dan Optika2/<K
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"/27B<AB9>3<23?7A/?/0B<8/B6/A/B;7=>703?:/9BContoh 6.16 )0%1-%31/0) !"4.%+!3%/A/E/<5;3<5/:/;71/1/A67>3?;3A?=>7E/7AB;/A/E/<5;3;7:797A7A79239/A:307603@/?2/?7>/2/ 1;2/<;3;7:797A7A798/B6A/967<55/(3<23?7A/1/1/A;/A/7<7A72/92/>/A;3:76/A03<2/E/<5239/AA3A/>72/>/A;3:76/A83:/@03<2/03<2/8/B6A/<>/03?/9=;=2/@7 /1/A7<7A3?8/279/?3<//2/:/6;/A/A72/92/>/A;3<8/2713;0B<5@30/5/7;/</;/A/<=?;/:970/A<E/0/E/<5/<03<2/239/A@3:/:B8/AB62703:/9/<5?3A7</,<AB9;3</<55B:/<571/1/A;/A/67>3?;3A?=>76/?B@27B>/E/9/</5/?0/E/<5/<A3>/A8/AB627?3A7</3?/?A7@303:B;@7</?2/A/<58/AB6>/2/:3<@/;/A/A3?:30762/6B:B@7</?2/A/<57<76/?B@;3<5B;>B:':369/?3</7AB>3<23?7A/6/?B@270/<AB23<5/<:3<@/13;0B<5:3<@/9=<C3?53<E/<5939B/A/<:3<@/<E/;/;>B;3;03<AB90/E/<5/<03<2/@367<55/A3>/A8/AB627?3A7</(3?6/A79/<!-"!1
5/?>3<23?7A/2/>/A;3:76/A03<2/03<2/239/A>/2/8/?/9A3?A3<AB>3<23?7A/?/0B<239/A6/?B@;3<55B</9/<:3<@/9/1/;/A/E/<5;3<56/@7:9/<0/E/<5/<;/E/2723>/<:3<@/>/2/8/?/9E/<5@/;/23<5/<A7A79239/A<E/K"/27B<AB9>3<23?7A/67>3?;3A?=>703?:/9BKK Gambar 6.44(a) Pada cacat mata hipermetropi,bayangan benda selalu jatuh dibelakang retina.(b) Cacat mata hipermetropi diatasidengan menggunakan lensacembung.benda dekatlensa cembungretina(a)(b)*3@3=?/<5E/<5;3<23?7A/67>3?;3A?=>7;3;7:797A7A79239/A
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1;
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134Mudah dan Aktif Belajar Fisika untuk Kelas X 1%2")/0)!3! 4!%/A/AB/;3;7:797=A=A@7:7/?E/<5A72/9:/570/79@3>3?A7>/2/;/A/<=?;/:970/A<E/93;/;>B/<=A=AB<AB903?/9=;=2/@7/A/B;3<5B0/68/?/94=9B@:3<@/;/A/A72/9@30/79@3>3?A7>/2/;/A/<=?;/:(3<23?7A/1/1/A>?3@07=>7;3;7:797A7A79239/A:307603@/?2/?7>/2/ 1;2/<A7A798/B6>/2/8/?/9A3?A3<AB@367<55/>3<23?7A/>?3@07=>7A72/92/>/A;3:76/A/A/B;3;0/1/>/2/8/?/9<=?;/:2/<A72/92/>/A;3:76/A03<2/8/B623<5/<83:/@ /1/A;/A/>?3@07=>72/>/A27A/<55B:/<57;3<55B</9/<:3<@/?/<59/> @3>3?A7>/2/!-"!1
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;2/<939B/A/<:3<@/ 27=>A?7Contoh 6.18110,5f 27=>A?7"/278/?/94=9B@:3<@//2/:/6
;2/<939B/A/<03@/?<E//2/:/6 27=>A?7Gambar 6.45Kacamata bifokal. Lensa (–) untukmelihat jauh, lensa (+) untuk melihatdekat.
23)'-!3)2-!@A75;/A7@;/;3?B>/9/<1/1/A;/A/E/<527/970/A9/<03<AB99=?<3/A72/90B<2/? /1/A;/A//@A75;/A7@;/2/>/A27A/<55B:/<5723<5/<:3<@/@7:7<2?7@$3<@/7<72/>/A;3<5B;>B:9/</A/B;3<E30/?9/<@7</?>/2/@/AB/?/6@/8/A/<>/;3;3<5/?B67/?/6:/7<2.Lup (Kaca Pembesar),<AB92/>/A;3:76/A03<2/03<2/9317:/5/?A/;>/9:307603@/?2/?7>/2/B9B?/<@303</?<E/275B</9/<:B>$B>;3?B>/9/<:3<@/13;0B<5Pada Contoh Soal 6.18, tandapositif menunjukkan bahwapenderita hipermetropi harusdibantu dengan lensa positif ataulensa cembung (lensa konvergen).Ingatlah
135Cahaya dan Optika/<5B:3?
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':369/?3</ 2/< ;/9/ %12!-!!. 7 ;3<8/27/A/B:3<@/>=@7A74*30/5/7;/</<2/93A/6B7:3<@/13;0B<5;3;7:79793;/;>B/<;3;03<AB90/E/<5/<;/E/E/<527>3?03@/?879/03<2/A3?:3A/927/<A/?/A7A794=9B@2/<:3<@/,<AB9:B>03<2/@3:/:B27:3A/99/<2/:/;?B/<5!@367<55/0/E/<5/</9/<A3?:3A/927?B/<5!-/E/<5/<E/<5A3?:3A/927?B/<5!-03?@74/A;/E/2/<A35/9@367<55/8/?/90/E/<5/<E/<52703<AB9:B>@3:/:B<35/A7403?A/<2/<35/A74(/2/@//A;3<55B</9/<:B>8/?/903<2/27B0/6B0/6@323;797/<?B>/@367<55/272/>/A9/<0/E/<5/<E/<5>/:7<583:/@0/57;/A/<=?;/:E/7AB>/2/8/?/90/1/E/<507/@/<E/ 1;(3?6/A79/<!-"!1
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"+/<>/:B>03<2/A3?:76/A23<5/<@B2BA@303@/?2/>B<879/;3<55B</9/<:B>03<2/A3?:76/A=:36;/A/23<5/<@B2BA@367<55/>3?03@/?/</<5B:3?<E/@303@/?Gambar 6.46Lup digunakan juga untuk memperjelastulisan yang sangat kecil.PPpGambar 6.47(a)Sudut penglihatan mata (),ketika benda dilihat tidakmenggunakan lup.(b) Sudut penglihatan mata (),ketika benda dilihat denganmenggunakan lup.FFp'(a)(b)sPs' = PP*30B/6:B>;3;7:7978/?/94=9B@
1; 7AB<5:/6>3?03@/?/<:B>879/;/A/;3:76/A03<2/23<5/<03?/9=;=2/@7>/2/8/?/9 1;Contoh 6.19
136Mudah dan Aktif Belajar Fisika untuk Kelas XmatapengamatbayanganLokulerbendasobs'obsokFokF 'obFobobjektif(a)Lokulerbendasobs'obsokFokF 'obFobobjektif(b)matapengamat=0 =9K
#3A3?/<5/<>/<8/<5;79?=@9=>=08/?/90/E/<5/<0/57:3<@/=0839A74=98/?/903<2/0/57:3<@/=9B:3?Gambar 6.49Pembentukan bayangan padamikroskop:a. Untuk mata berakomodasimaksimum;b. Untuk mata tidak berakomodasi.(3?6/A79/<!-"!1
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/E/<5/</967?E/<5276/@7:9/<=:362B/:3<@/2/:/;;79?=@9=>03?@74/A;/E/27>3?03@/?2/<A3?0/:79A3?6/2/>03<2/@3;B:/Gambar 6.48Mikroskoplensaobjektifbendalensaokuler!5!" 793A/6B7 1;
1;/ (3?03@/?/</<5B:3?/<5B:3?93A79/;/A/03?/9=;=2/@7>/2/8/?/9 1;,<AB9;3<567AB<5>3?03@/?/<7<7275B</9/< %12!-!!. 7 03?79BA/<5B:3?%&7:/7%27>3?=:3623<5/<>3?@/;//<03?79BA ' ' 1; 1;
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137Cahaya dan Optika•Apabila jarak bayangan yangdihasilkan lup adalah (s’ = –x),artinya mata berakomodasipada jarak x sehinggaperbesaran sudutnya adalahangulerPPPPM=+fx•Untuk mata berakomodasimaksimum, bayangan yang di-bentuk oleh lup terletak dititik dekat mata (s’ = –PP)s’ = –x = –PPx = PPangulerPPPPM=+fPPPP=+f1•Untuk mata tidakberakomodasi, bayangan yangdibentuk oleh lup terletak dititik jauh mata (s’ = –PR).Untuk mata normal,PR = maka s’ = . Agarjarak s’ = – maka bendaharus diletakkan di titikfokus F.s’ = –x = – x = angulerPPPPM=+fxPP=+f0PP=fIngatlah(3?03@/?/<=:36:3<@/=0839A74/2/:/6=0=0 =0=0 =0 K
<=9=9K
=0L=9K
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#3A3?/<5/< 8/?/9A7A79239/A;/A/<=?;/:=98/?/94=9B@=9B:3?,<AB9;/A/A72/903?/9=;=2/@7Tantanganuntuk AndaPelangi adalah hasil peristiwa optikayang melibatkan butiran hujan,cahaya matahari, dan mata.Gambarkan peristiwa optikatersebut sehingga Andamendapatkan sensasi keindahan itu.*30B/6;79?=@9=>;3;7:797:3<@/=0839A7423<5/<8/?/94=9B@ 1;2/<:3<@/=9B:3?23<5/<8/?/94=9B@1;"79/8/?/9/<A/?:3<@/ 1;67AB<5>3?03@/?/<A=A/:;79?=@9=>>/2/@//A/ ;/A/03?/9=;=2/@7;/9@7;B;0 ;/A/A72/903?/9=;=2/@7!5!" 793A/6B7=0 1;
1;=91;/ (3?03@/?/<>/2/@//A;/A/03?/9=;=2/@7;/9@7;B;;/A/27/<55/><=?;/:=9K 1;=9 =9=9 =9 =9=9 =9 =9=9=9 =9 =9 =9=9=9 =9 =91;K 1; K
1;K 1; K 1; K
1;=91;Contoh 6.213?2/@/?9/<?B;B@
=0 =9 =0=0 K 1; 3<5/<;3<55B</9/<?B;B@:3<@/A7>7@27>3?=:36=0 =0=0 =0 =0=0 =0 =0=0=0 =0 =0 =0=0=0 =0
138Mudah dan Aktif Belajar Fisika untuk Kelas X(3?03@/?/<=:36:3<@/=9B:3?=9=9 1; 1; "/27>3?03@/?/<A=A/:;79?=@9=>>/2/@//A;/A/03?/9=;=2/@7;/9@7;B;/2/:/6=0L=9 9/:70 ,<AB9;/A/A72/903?/9=;=2/@7=9=91;=0 =9 =01;=0
1;3?2/@/?9/<?B;B@:3<@/A7>7@=0 =0=0 =0 =0=0 =0 =0=0 =0 =0 =0=0=0 =0 1;
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Tugas Anda 6.2Anda mungkin pernah melihathasil suatu pencitraan luar angkasayang diperoleh dari teleskopHubble. Bagaimanakah prinsipFisika yang diterapkan padateleskop luar angkasa tersebut?4.Teropong atau Teleskop+3?=>=<5/A/BA3:3@9=>;3?B>/9/</:/A=>A79E/<52/>/A275B</9/<B<AB9;3:76/A03<2/03<2/E/<58/B6@367<55/A/;>/9:3076239/A2/<:307683:/@(/2/
!,),%/;3;0B/A@30B/6A3:3@9=>E/<5A3?27?7/A/@2B/:3<@/2/<@30B/6>7>/=?5/</@30/5/7A/0B<5<E/*3A3:/67AB!,),%/8B5/;3;0B/A03?;/1/;;/1/;A3:3@9=>2/<;3<3;B9/<0/<E/9>3<3;B/<2/:/;072/<5@A?=<=;7*39/?/<52793</:2B/;/1/;A3:3@9=>E/7ABA3:3@9=>07/@2/<A3:3@9=>>/<AB: +3:3@9=>07/@A3?27?7/A/@0303?/>/:3<@/E/<503?4B<5@7;3;07/@9/<@7</?2/A/<52/?703<2/+3:3@9=>E/<5A3?;/@B99/A35=?7A3:3@9=>07/@27/<A/?/<E/A3:3@9=>07<A/<5A3:3@9=>B;7A3:3@9=>>/<55B<52/<A3:3@9=>>?7@;/ +3:3@9=>>/<AB:A3?27?7/A/@0303?/>/13?;7<@30/5/7>3;/<AB:2/<:3<@/@30/5/7>3;07/@@7</?2/A/<52/?703<2/! %,%2+/0).3!.'+3:3@9=>07<A/<5A3?27?7/A/@2B/:3<@/E/7AB:3<@/=0839A742/<:3<@/=9B:3?!-"!1 03?79BA7<7;3<B<8B99/<>?=@3@>3;03<AB9/<0/E/<5/</967?2/?7@B/ABA3:3@9=>07<A/<5=0 1; 1;
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139Cahaya dan Optikaobjektif(+)okuler(–)Ls'obsoksob = ~s'ok = – ~matapengamatGambar 6.50Pembentukan bayangan olehteleskop bintang pada mata yangberakomodasi maksimum.=0=9K
(/<8/<5A3:3@9=>07<A/<5879/;/A/03?/9=;=2/@7/2/:/6K
/<>/<8/<5A3:3@9=>07<A/<5>/2/@//AA72/903?/9=;=2/@7/2/:/6=0=9#3A3?/<5/<>/<8/<5A3?=>=<5=98/?/903<2/0/57:3<@/=9B:3?=08/?/90/E/<5/<0/57:3<@/=0839A74=08/?/94=9B@:3<@/=0839A74=98/?/94=9B@:3<@/=9B:3?(3?03@/?/</<5B:3?A3:3@9=>07<A/<5/2/:/6A/<A/<a/A/B=0/<5B:3?=9#3A3?/<5/</<5B:3?>3?03@/?/</<5B:3?K (/2/@//A53?6/</%/A/6/?7@3=?/<5>3<3:7A753?6/</;3<5/;/A7<E/23<5/<@30B/6A3:3@9=>07<A/<5$3<@/=0839A742/<=9B:3?E/<5275B</9/<;3;7:7978/?/94=9B@;/@7<5;/@7<5
1;2/< 1;"79/@B2BA27/;3A3?%/A/6/?727:76/A23<5/<;/A/A3:/<8/<5
I03?/>/23?/8/A@B2BA27/;3A3?%/A/6/?7>/2/@//A27/;/A7;3<55B</9/<A3:3@9=>07<A/<5A3?@30BA!5!" 793A/6B7=0
1;=9 1;
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1;J (/2/:3<@/=9B:3?,<AB9;3<5/;/A703<2/:/<57A07/@/<E/;/A/A72/903?/9=;=2/@7/E/<5/<=:36:3<@/=9B:3?6/?B@8/AB627A7A79A/967<55/=9"79/0/E/<5/<A3?:3A/927A/967<55/2/>/A27>/@A79/<03<2/03?/2/274=9B@=9=9 1;Contoh 6.22
140Mudah dan Aktif Belajar Fisika untuk Kelas X# %,%2+/0 1)2-!+3:3@9=>>?7@;/27@30BA8B5/A3:3@9=>07<=9B:3? B<5@7A3:3@9=>7<7@/;/23<5/<A3:3@9=>B;7"79/>/2/A3:3@9=>B;727:3<59/>723<5/<:3<@/>3;0/:79@32/<59/<A3:3@9=>>?7@;/27:3<59/>723<5/<>?7@;/@79B@79B B<5@7>?7@;/7<7B<AB9;3;0/:799/<0/E/<5/<(3<55B<//<>?7@;/27;/9@B29/</5/?A3:3@9=>7<7A72/9A3?:/:B>/<8/<52/<>?/9A7@B<AB9275B</9/<+3:3@9=>>?7@;/27AB<8B99/<>/2/!-"!1 *3A7/>A3:3@9=>>?7@;/07/@/<E/27:3<59/>723<5/<7<4=?;/@7<=;=?@3>3?A7L
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<59/>3?A/;/;3<B<8B99/<>3?03@/?/<2/</<59/932B/;3<B<8B99/<27/;3A3?:3<@/=0839A742/:/;;7:7;3A3?$ %,%2+/0!,),%) %,%2+/0 !.''4.'+3:3@9=>7<7;3?B>/9/<;=27479/@72/?7A3:3@9=>B;7(3;0/:79/<0/E/<5/<2/:/;A3:3@9=>7<727:/9B9/<23<5/<;3<55B</9/<:3<@/139B<5@30/5/7:3<@/=9B:3?<E/+3:3@9=>7<7@3?7<58B5/27@30BAA3:3@9=>>/<55B<5/A/BA3:3@9=> /:7:37(3?6/A79/<!-"!1 Gambar 6.52Teleskop prismaobjektifokulerokulerGambar 6.51Pembentukan bayangan padateleskop Bumi oleh mata yangberakomodasi maksimum.Pada teropong bintang ....(1) bayangan oleh lensa objektifterletak di titik api II.(2) titik api II lensa objektifdiimpitkan dengan titik api Ilensa okuler(3) bayangan akhir terletak di takterhingga(4) bayangan akhir terbalikUMPTN, 1993Jawaban : DPembahasan SoalJ (3?03@/?/<A3:3@9=>=0=9
1; 1;
9/:7"/27@B2BA27/;3A3?;/A/6/?793A79/27/;/A7;3<55B</9/<A3:3@9=>/2/:/6
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>/<8/<5A3:3@9=>B;7pembentuk(+)okuler(+)objektif(+)fobfobFob4fpfokFpFpFokFokSumber: Jendela Iptek, 1997matapengamat
141Cahaya dan Optikabayangansob = ~okuler(–)objektif(+)s'obsokFokFobFokmatapengamatGambar 6.53Pembentukan bayangan olehteleskop panggung oleh mata yangberakomodasi.*30B/6A3:3@9=> /:7:37E/<5;3;7:797>3?03@/?/</<5B:3? 9/:72/<;3;7:7978/?/94=9B@=0839A74
1;275B</9/<B<AB9;3<E3:72797@30B/603<2/E/<5A3?:3A/9@/<5/A8/B6 7AB<5>/<8/<5A3:3@9=> /:7:377<7!5!" 793A/6B7=0
1;/<5B:3? 9/:7':369/?3</2/:/;A3:3@9=>7<7:3<@/=9B:3?<E/:3<@/139B<503?/?A7=903?<7:/7<35/A74"/278/?/94=9B@:3<@/=9B:3?/2/:/6K
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2/>B<>/<8/<5A3:3@9=> /:7:37@303@/?
=0=9KContoh 6.23Tugas Anda 6.3Anda mengenal ada dua macamteleskop, yaitu teleskop bias danteleskop pantul. Mengapateleskop pantul yang berukuranbesar lebih mudah dibuatdibandingkan dengan teleskopbias?% %,%2+/0 !.34,+3:3@9=>7<727:3<59/>723<5/<13?;7<139B<503@/?@30/5/713?;7<=0839A74<E/*3:/7<7AB27:3<59/>7>B:/23<5/<13?;7<2/A/?2/<:3<@/13;0B<5@30/5/7=9B:3?<E/ 3?;7<2/A/?03?4B<5@7B<AB9;3;/<AB:9/<1/6/E/':369/?3</7ABA3:3@9=>7<727@30BAA3:3@9=>>/<AB:(3?8/:/</<@7</?E/<5A3?8/27>/2/A3:3@9=>>/<AB:27AB<8B99/<=:36!-"!1
sinar sejajar daribintang/bulanyang jauhcermincekunglensa cembung(okuler)FGambar 6.54Teleskop pantul
142Mudah dan Aktif Belajar Fisika untuk Kelas X*30B/69/;3?/;3;7:797A7A79/>7
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/?A7<E/:3<@/9/;3?/6/?B@2753@3?;3<8/B6747:;Gambar 6.56Penjalaran sinar pada kameraContoh 6.24cahayakacaprisma& !-%1!#/;3?//2/:/6/:/AB<AB9;3?39/;5/;0/?2/?7@B/AB=083903?B>/A3;>/A/A/B>3?7@A7D/(?7<@7>93?8/9/;3?/;7?7>23<5/<;/A/$3<@/9/;3?/;3?B>/9/<0/57/<2/?79/;3?/E/<503?4B<5@7B<AB9;3;03<AB90/E/<5/<;7?7>:3<@/;/A/>/2/;/A/#/;3?/27:3<59/>723<5/<47:;E/<503?4B<5@7@30/5/7A3;>/A0/E/<5/<;7?7>23<5/<?3A7</>/2/;/A/"79/;/A/;3;7:79793;/;>B/<B<AB903?/9=;=2/@7>/2/9/;3?/>3<5/AB?/<0/E/<5/</5/?8/AB6A3>/A>/2/47:;27:/9B9/<23<5/<1/?/;3<553?/99/<:3<@/!-"!1 ;3<B<8B99/<@30B/69/;3?/:3<59/>23<5/<0/57/<0/57/<<E/(?=@3@>3<5/;07:/<5/;0/?=:369/;3?//2/:/6@30/5/703?79BA*3A3:/69/;3?/27072799/<93=0839E/<5;3<8/27>3?6/A7/<:/:B8/?/9/<A/?/:3<@/2/<47:;27/AB?@367<55/0/E/<5/<A3>/A8/AB6>/2/47:;#3;B27/<A=;0=:>3;0B9/27A39/< /6/E/@353?/;/@B9;3:/:B7:3<@/B<AB9;3;03<AB90/E/<5/<>/2/47:;@3:/;/@3:/<5D/9AB>3;0B9/1/6/E/A3?0B9/2/<0/E/<5/<2747:;A3?03<AB9(/2/!-"!1 @30B/6>?7@;/275B</9/<>/2/0303?/>/9/;3?/?34:39@:3<@/AB<55/:
;=23?< /:/;9/;3?/7<7>?7@;/275B</9/<B<AB9;3;03:=99/<1/6/E/67<55/2/>/A03?>BA/?;3<53:7:7<570/57/<2/:/;9/;3?//5/?4=A=5?/43?2/>/A;3:76/A5/;0/?/9AB/:E/<5/9/<27/;07:<E/;3:/:B7:3<@/9/;3?/Gambar 6.55Kamera dan bagian-bagiannyakacalensacahayaprismafilmlensaprismamatakacacahayaKata Kunci•daya akomodasi•punctum proximum•punctum remotum•emetropi•miopi•hipermetropi•presbiopi•astigmatisma•lup•mikroskop•teropong/teleskop•teleskop bintang•teleskop bumi•teleskop Galilei•kamera
143Cahaya dan Optika<2/07@/;3;>3?=:36B?/7/<;/A3?7;3<53</70/07<723<5/< 27$$$ /A/B23<5/<;3<5B<8B<57@7AB@7<A3?<3A;3<53</71/6/E/2/<=>A79/@27/<A/?/<E//2/:/627 ! ""
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