物理,十萬個thx

這是若以近似的計算方法，將水晶球看作一凸透鏡。則依造鏡這公式，水晶球的焦距為
(1/f) = (n-1)[(1/r1) + (1/r2)]
n = 1.724，r1 = r2 = 100/2 = 50mm
(1/f) = (1.724-1)[(1/50) + (1/50)]
f = 34.53mm
再用成像公式
(1/u) + (1/v) = (1/f)
v = uf/(u – f)
v = 34.53x600 / (600 – 34.53)
v = 36.64mm