antar lampu mobil berjarak 61cm dengan panjanh gelombang 800nm. Jika diameter pupil mata 4mm, tentukan berapa km jarak pengamat orang terhadap mobil!

jarak dua lmapu, dm = 61 cm = 61.10⁻² m
panjang gelombang, λ = 800 nm = 8.10⁻⁷ m
diameter pupil, D = 4 mm = 4.10⁻³ m
jarak pengamat, L = _____ km

dm = 1,22 λ.L/D
61.10⁻² = (1,22)(8.10⁻⁷)(L)/4.10⁻³
61.10⁻² = (2,44.10⁻⁴)(L)
L = 2500 m
L = 2,5 km