SOAL FISIKA

Dik: cermin cekung

M = 2x

S = 22 cm

Dit: S’ dan  f = ... ?

Jawban :

·         M  = I S’/S I

2   = S’/22

2x22  = S’

S’       =  44 cm

·         1/f = 1/S’ + 1/S

1/f = 1/5 + 1/44

1/f = 2+1/44

1/f = 2/44

F = 44/2 = 14,6 cm

11. Dik : cermin cekung

h =h

S= 4 cm

R = 14 cm

Dit : sifat bayangan yang dibentuk ?

Jawab :

 ‘’ gambar difoto ‘’

Maya, tegak, diperbesar

12. Dik: cermin cekung

S = 25 cm

M = 4x

Dit: f = ... ?

Jawab :

·         M = I S’/S I

4 = S’/25

4x25 = S’

S’ = 100 cm

·         1/f = 1/S + 1/S’

1/f = 1/25 + 1/100

1/f  = 1+4/100

1/f = 5/100

F = 100/5 = 20 cm

13. Dik : cermin cekung

S = 20 cm

R = 60 cm

Dit: letak bayangan dan sifat bayangan ?

Jawab :

‘’ gambar difoto’’

Dibelakang cermin, sifat : maya, diperbesar, tegak.

14. Dik: cermin cembung

F = -8 cm

S’ = 6 cm

Dit: S’ ..?

Jawab :

1/f = 1/S + 1/S’

-(1/8)= 1/6 + 1/S’

-(1/8) – 1/6 = 1/S’

-3-4/24 = 1/S’

-7/24 = 1/S’

-24/7 = S’

S’ = -3,42 cm

15. Dik : cermin cembung

S = 16 cm

S’ = -28,5 cm

Dit: f =..?

Jawab :

1/f = 1/S + 1/S’

1/f = 1/16 + (-1/28,5)

1/f = (28,5/456) – (16/456)

1/f = 12,5/456

1/f = 456/ 12,5

 F = 36, 48 cm

F = -36,48 cm (cermin c