Question

Benda sejumlah 20 cm di depan lensa cembung dengan fokus 25 cm.
hitung:
a.jarak bayangan
b.kekuatan lensa

Answer 1

A) 1/f = 1/s + 1/s'
    1/25 = 1/20 + 1/s'
    1/25 - 1/20 = 1's'
    -1/100 = 1/s'
    100 = -s'
    -100 = s'

b) P = 100/f
       = 100/25
       = 4 dioptri

Answer 2

diket = so = 20

f = 25

ditanya = si..?

kekuatan lensa..?

dijawab = 1/f= 1/si + 1/so

1/25 = 1/si + 1/20

1/25 - 1/20 = 1/si

4/100 - 5/100 = 1/si

-1 /100 = 1/si

-100 = si