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494569>9B9;1> B521719 @5A21>49>71> 1>C1A1 25B1A C9>779 21H1>71> 41>
25B1A C9>779 25>41 ,531A1 =1C5=1C9B 41@1C 49CD<9B
f
SU
/ % O
L F P
/ % R

c. Pemantulan pada Cermin Cembung Gambar 6.15
Bagian-bagian cermin cembung
5A=9> 35=2D>7 141<18 35A=9> H1>7 =5=9<9;9 @5A=D;11> 35=2D>7 R = jari-jari kelengkungan cermin
5A=9> 35=2D>7 25AB961C 49E5A75> H19CD 25AB961C =5=1>31A;1> B9>1A P = titik pusat kelengkungan cermin
1791> 21791> 35A=9> 35=2D>7 B5@5AC9 @141 $0%$4 F = titik fokus cermin
f = jarak titik fokus ke cermin
(0%(167.$1 %$:$1*$1 2/(+ &(40,1 &(0%71*
,52D18 25>41 H1>7 49<5C1;;1> 49 45@1> B52D18 35A=9> 35=2D>7 =5 c
=9<9;9 21H1>71> 45>71> B961C B961C C5AC5>CD 1H1>71> B52D18 25>41 ?<58 35A=9>
35=2D>7 41@1C 49C5>CD;1> 45>71> 31A1 =5>771=21A;1> 41A9 B9>1A 9BC9=5F1 a b
@141 35A=9> 35=2D>7 )5A81C9;1> $0%$4 )141 $0%$4 C5A<981C
1 B9>1A 41C1>7 H1>7 B5:1:1A BD=2D DC1=1 49@1>CD<;1> B51;1> 1;1> O F P
41C1>7 41A9 C9C9; 6?;DB
2 B9>1A 41C1>7 H1>7 =5>D:D C9C9; 6?;DB 49@1>CD<;1> B5:1:1A 45>71>
BD=2D DC1=1 Gambar 6.16
Sinar-sinar istimewa pada cermin
3 B9>1A 41C1>7 H1>7 =5>D:D C9C9; @DB1C ;5<5>7;D>71> 35A=9> 49@1> cembung
CD<;1> ;5=21<9 =5<1<D9 <9>C1B1> H1>7 B1=1
1A1 =5<D;9B 21H1>71> 25>41 ?<58 35A=9> 35=2D>7 C5A<981C B5@5AC9
@141 $0%$4 )141 31A1 C5AB52DC B9>1A 9BC9=5F1 H1>7 497D>1;1>
141<18 B9>1A 41> B9>1A 5A41B1A;1> 71=21A 21H1>71> C5AB52DC 41@1C
49B9=@D<;1> 218F1 25>41 H1>7 49<5C1;;1> 49 45@1> B52D18 35A=9> 35=
2D>7 B5<1<D =5>781B9<;1> 21H1>71> =1H1 C571; 41> 49@5A;539< O F P
7075 3$'$ &(40,1 &(0%71*
+D=DB @141 35A=9> 35=2D>7 B1=1 B5@5AC9 AD=DB H1>7 25A<1;D @141 Gambar 6.17
35A=9> 35;D>7 H19CD Lukisan pembentukan bayangan oleh
cermin cembung
#

% /

% /

L

!1< 81< H1>7 @5A<D 49@5A81C9;1> 141<18
1 C1>41 :1A1; 6?;DB @141 35A=9> 35=2D>7 B5<1<D 25A>9<19 >571C96 !1<
9>9 49B5212;1> <5C1; C9C9; 6?;DB @141 35A=9> 35=2D>7 C5A<5C1; 49
25<1;1>7 35A=9>
2 D>CD; 25>41 >H1C1 49 45@1> 35A=9> 35=2D>7 B5<1<D C5A25>CD;
2 D>CD; 25>41 >H1C1 49 45@1> 35A=9> 35=2D>7 B5<1<D C5A25>CD;
21H1>71> =1H1 #149 >9<19 B @141 35A=9> 35=2D>7 25AC1>41 >571C96
21H1>71> =1H1 #149 >9<19 / @141 35A=9> 35=2D>7 25AC1>41 >571C96

Contoh 6.4
,52D18 35A=9> 35;D>7 =5=9<9;9 :1A9 :1A9 ;5<5>7;D>71> = ,52D18 25>41 49<5C1;;1> @141
:1A1; = 41A9 35A=9> C9>779 25>41 3= !9CD>7<18 <5C1; C9>779 41> @5A25B1A1> 21H1>71>
$9$%
9;5C18D9

Cahaya dan Optika 115