1/F = (n-1)·(1/R₁ + 1/R₂)
1/F = (1,5 - 1)·(1/4 + 1/6)
1/F = (5/10)·(5/12)
1/F = 25 / 120
F = 120 / 25 = 4,8 см
1/F = (n-1)·(1/R₁ + 1/R₂)
1/F = (1,5 - 1)·(1/4 + 1/6)
1/F = (5/10)·(5/12)
1/F = 25 / 120
F = 120 / 25 = 4,8 см