फोकस दूरी कैलकुलेटर — सूत्र

Focal Length

The focal length defines the converging or diverging power of a lens or mirror.

Formula

1/f = 1/d_o + 1/d_i

Lens power in diopters is D = 1/f (with f in meters). Positive focal length = converging lens; negative = diverging.

हल किया गया उदाहरण

An object at 30 cm produces an image at 15 cm.

  1. 1/f = 1/do + 1/di
  2. 1/f = 1/30 + 1/15
  3. 1/f = 0.0333 + 0.0667 = 0.1
  4. f = 10 cm
  5. Power = 100/10 = 10 diopters