PhysicsThe Human Eye and the Colourful World

Combining Lens Powers

Powers add up when thin lenses are placed in contact.

Power of lens 14 D

Power of lens 2-2 D

Net power

Net focal length

50cm

Behaves like

Convex lens

Ray diagram — lensNet power: 2 D

Click to start animation

P = P₁ + P₂ for lenses in contact; unit of power is the dioptre (D).

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