Physics Laws & Theorems
Intermediate

Lens Maker's / Thin Lens

Relates focal length to object and image distances for a thin lens.

Formula

1f=1v−1u\frac{1}{f} = \frac{1}{v} - \frac{1}{u}

Variables

fFocal length
vImage distance
uObject distance

Example

An object 30 cm from a 10 cm-focal-length lens forms an image at 15 cm.

Did You Know?

This equation lets opticians grind lenses to precise focal lengths for glasses and cameras.

opticslenslaw