Question

Which shows the correct lens equation?

The inverse of f equals the inverse of d Subscript o Baseline times the inverse of d Subscript I Baseline.
The inverse of f equals StartFraction d Subscript o over d Subscript I Baseline EndFraction plus StartFraction d Subscript I Baseline over d Subscript o Baseline EndFraction.
The inverse of f equals the inverse of d Subscript o Baseline minus the inverse of d Subscript I Baseline.
The inverse of f equals the inverse of d Subscript o Baseline plus the inverse of d Subscript I Baseline.

Answer 1

The correct lens equation is

1/f = 1/do + 1/di

(where do = object distance, di = image distance).