sebuah benda diletakkan 30 cm didepan cermin cekung yang berjari jari 20 cm. Tentukan = jarak bayangan, perbesaran bayangan, sifat bayangan

s => 30 cm
r => 20 cm
f => 1/2 r => 10 cm

1/s + 1/s' => 1/f
1/30 + 1/s' => 1/10
1/s' => 1/10 - 1/30
1/s' => 3/30 - 1/30
1/s' => 2/30
s' => 15

M => s'/s
M => 15/30
M => 1/2 kali

sifat bayangan => Nyata, terbalik, diperkecil,