1Which of these has the same dimensions as length?
Length and de Broglie wavelength both have the dimensions [L].
SI base quantitiesClass 11, Units and Measurements
Dimensional formula of Length
[L]
One of the seven SI base quantities. Distance, height, radius, width and displacement all share its dimension.
How to get the dimensional formula of length
- Length is one of the seven SI base quantities, so its dimension is written directly: [L].
Quantities with the dimensions [L]
- Displacement
- Radius of gyration
- Mean free path
- Wavelength
- Amplitude
- Focal length
- Fringe width
- de Broglie wavelength
- Bohr radius
Equal dimensions do not make them the same quantity. Compare length with the others in the full grid.
Three questions on length
2What is the SI unit of length?
The SI unit of length is the metre (m).
3Which one has different dimensions from the others?
Time is [T]. The other three are all [L].
An equation that uses length
Equation checker
Matching dimensions are necessary, not sufficient. A check cannot see pure numbers such as 1/2 or 2π, so a consistent equation can still be wrong.
Read as
T = 2 π sqrt(l / g)T[T]=2 pi sqrt(l/g)[T]Dimensionally consistentEvery term is [T]
l = lengthg = acceleration due to gravity
Length: quick answers
What is the dimensional formula of length?
The dimensional formula of length is [L]. It is one of the seven SI base quantities.
What is the SI unit of length?
The SI unit of length is the metre (m).
Which quantities have the same dimensions as length?
Length shares [L] with displacement, radius of gyration, mean free path, wavelength, amplitude, focal length, fringe width, de Broglie wavelength. Equal dimensions do not make them the same quantity.