Question

what are dimensional variales ,dimensinal constants,quantities which have units but no dimension,quantities which have no units but have dimension& quantities which does'nt have both units &dimension.give some examples also?

Answer 1

Dimensionless quantity with a unit:

θ = b/d

Here θ is dimensionless but its unit is degree or radian. Eg angle, solid angle.

Physical quantities which have no units do not have dimensions.

Dimensionless quantities with no units: refractive index, coefficient of friction, relative permeability or relative permittivity.