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b. Pemantulan pada Cermin Cekung
5A=9> 35;D>7 141<18 35A=9> H1>7 =5=9<9;9 @5A=D;11> 35;D>7 B
5A=9> 35;D>7 25AB961C ;?>E5A75> H19CD 25AB961C =5>7D=@D<;1> B9>1A
1791> 21791> 35A=9> 35;D>7 C1=@1; B5@5AC9 @141 $0%$4 P F O
(0%(167.$1 %$:$1*$1 2/(+ &(40,1 &(.71*
%5C1; 41> B961C 21H1>71> H1>7 4925>CD; ?<58 35A=9> 35;D>7 25A71>CD>7 f
@141 <5C1; 25>41 ,52D18 25>41 H1>7 49<5C1;;1> 49 45@1> B52D18 35A=9>
35;D>7 1;1> =5=9<9;9 21H1>71> 45>71> B961C B961C C5AC5>CD )5A81C9;1> R
$0%$4 B961C B961C 35A=9> 35;D>7 49 1>C1A1>H1 f = jarak fokus
1 ,9>1A 41C1>7 H1>7 B5:1:1A BD=2D DC1=1 49@1>CD<;1> =5<1<D9 C9C9; R = kelengkungan cermin
6?;DB DC1=1 Gambar 6.8
Bagian-bagian cermin cekung
2 ,9>1A 41C1>7 H1>7 =5<1<D9 C9C9; 6?;DB DC1=1 49@1>CD<;1> B5:1:1A
45>71> BD=2D DC1=1
3 ,9>1A 41C1>7 H1>7 =5<1<D9 C9C9; @DB1C ;5<5>7;D>71> 35A=9> 1;1> a)
49@1>CD<;1> ;5=21<9 =5<1<D9 <9>C1B1> H1>7 B1=1 c) b) F
1H1>71> B52D18 25>41 ?<58 35A=9> 35;D>7 41@1C 49C5>CD;1> 45>71> P O
31A1 =5>771=21A;1> 41A9 B9>1A 9BC9=5F1 @141 35A=9> 35;D>7 1A1
=5<D;9B 21H1>71> 25>41 ?<58 35A=9> 35;D>7 141<18 B521719 25A9;DC Gambar 6.9
)5A81C9;1> $0%$4 +$( % -".0 * 35A=9> 35;D>7 4971=21A Sinar istimewa pada cermin
<5>7;1@ 45>71> 21791> 21791>>H1 +$( % ("!1 71A9B 4971=21A cekung
D>CD; =5<1=21>7;1> C9>779 25>41 41@D> 71A9B C941; @5A<D C5A<1<D
C9>779 +$( % ("0&$ 71=21A;1> B9>1A 9BC9=5F1L +$( % (""*- 0 B III II I
71=21A;1> B9>1A 9BC9=5F1L +$( % (")&* C9C9; H1>7 =5AD@1;1>
@5A@?C?>71> 1>C1A1 B9>1A @1>CD<L 41> B9>1A @1>CD<L 4925A9 >1=1 A'
-9C9; 9>9 =5AD@1;1> 21H1>71> 41A9 C9C9; $5=D491> 71A9B C571; <DADB A P F O
BD=2D DC1=1 49C1A9; 41A9 C9C9; ;5 1A18 BD=2D DC1=1 -9C9; 9>9 4925A9 B'
>1=1 H1>7 =5AD@1;1> 21H1>71> 41A9 C9C9; B589>771 =5AD@1;1>
21H1>71> 41A9 71A9B
Gambar 6.10
III II I III II I Pembentukan bayangan di ruang III
AB pada cermin cekung
B B'
B
A' O
P A F O P F A A'
S S'

B'

Gambar 6.11 Gambar 6.12
Gambar bayangan jika letak bendanya di Gambar bayangan jika bendanya di
ruang II ruang I
5A41B1A;1> $0%$4 $0%$4 41> $0%$4 41@1C
49B9=@D<;1> 218F1
1 :9;1 25>41 @141 AD1>7 " =1;1 21H1>71> H1>7 4981B9<;1> 141<18
=1H1 C571; 41> 49@5A25B1A
2 :9;1 25>41 25A141 49 AD1>7 "" =1;1 21H1>71> H1>7 4981B9<;1> 141<18
>H1C1 49 AD1>7 """ C5A21<9; 41> 49@5A25B1A
3 :9;1 25>41 25A141 @141 AD1>7 """ =1;1 21H1>71> H1>7 4981B9<;1>
141<18 >H1C1 49 AD1>7 "" C5A21<9; 41> 49@5A25B1A

Cahaya dan Optika 113