How to derive it
Start from a formula that defines strain, then replace each quantity with its dimensions. M is mass, L is length, T is time.
- strain = change in length ÷ original length = [L] ÷ [L]
- So [strain] = [M⁰L⁰T⁰].
Same dimensions as strain: refractive index, coefficient of friction. JEE often asks which pairs match.
Dimensional formulas of other quantities
The full searchable list, with SI units, is on the dimensional formula page.
Questions students ask
What is the dimensional formula of strain?
[M⁰L⁰T⁰], from strain = ΔL ÷ L. Its SI unit is no unit.
What are the dimensions of strain?
Strain is dimensionless: it's a ratio of two quantities with the same dimensions.
What is the SI unit of strain?
no unit.
Which quantities have the same dimensions as strain?
refractive index, coefficient of friction, all [M⁰L⁰T⁰].