Dimensional formula of power of a lens

Power of a lens

[L⁻¹]

Written in full: [M⁰ L⁻¹ T⁰ A⁰ K⁰]

How to derive it

Power of a lens = 1 ÷ Focal length

Put in the dimensions of each part: 1 ÷ [L] = [L⁻¹].

mass (M): 0
length (L): -1
time (T): 0
current (A): 0
temperature (K): 0

SI unit

The SI unit of power of a lens is dioptre (D).

Same dimensions as power of a lens

These quantities have exactly the same dimensions, a favourite trick in JEE and NEET "which pair has the same dimensions" questions:

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