How to derive it
Start from a formula that defines Rydberg constant, then replace each quantity with its dimensions. M is mass, L is length, T is time.
- The bracket is a pure number.
- R = (1/λ) ÷ number = 1 ÷ [L]
- So [Rydberg constant] = [L⁻¹], also written [M⁰L⁻¹T⁰].
Same dimensions as Rydberg constant: wave number, power of a lens. 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 Rydberg constant?
[L⁻¹] (or [M⁰L⁻¹T⁰]), from 1/λ = R(1/n₁² − 1/n₂²). Its SI unit is m⁻¹.
What are the dimensions of Rydberg constant?
M: 0, L: -1, T: 0.
What is the SI unit of Rydberg constant?
m⁻¹.
Which quantities have the same dimensions as Rydberg constant?
wave number, power of a lens, all [L⁻¹].