What Are The Physical Dimensions Of

Do all the physical quantities have dimensions?

No.Counterexamples include the coefficient of friction, the fine structure constant, and even such parameters as number of particles and angles [although that depends somewhat on your definition of “dimensions”; for instance, angles arguably have units of “radians,” and number of particles arguably has units of “particles.”]In fact, even if you had only physically dimensionful quantities initially, their ratios may (sometimes) be dimensionless, in which case you would have a physical quantity (their ratio) without dimensions.E.g., if you have two masses, their ratio is a dimensionless physical quantity.This is of importance for the Buckingham π theorem, which basically tells you what your “physically interesting” quantities are.In fact, due to that thorem, the quantities without dimensions are almost always the most important ones, because these are the ones whose actual, numerical values don’t change depending on the units you measure them in, and can thus be fairly described as “small” or “large” (compared to 1, which is typically physically meaningful in such cases).Furthermore, an area of great interest in theoretical physics is those models which are, in essence, entirely dimensionless (do not depend at all on scale). In quantum field theory, such a theory is known as a conformal field theory, and is an area of modern research.

What are the physical dimensions of an electron?

It is often said that the electron is a point particle with no dimensions, but that isn’t quite right. An electron is a quantum mechanical object which is described by a wavefunction. One consequence of this is that the position and the momentum of the electron cannot both be know to an arbitrary precision. When the momentum of an electron is well known, the position becomes more uncertain. For example, if an electron is in an orbital of an atom its momentum is well known, so the position is uncertain.The key point is that in an atom an electron acts as if it fills the entire orbital; you could say that it’s size is the size of the orbital! Now you can pinpoint its position more precisely by probing it with a high energy photon or other particle; the more high energy the more precise the position and the smaller the electron will look. There is no known limit to how high an energy you can use, and so there is no known lower limit to the size of an electron, but in most everyday object the electron acts like it is about the size of an atom’s orbital.

What are two physical quantities which have the same dimensions?

Speed and velocityEnergy and work and moment of forcePressure and stress and Young's modulusImpulse and momentumWeight and force and upthrustElectric resistance and impedanceDensity and molar concentrationSurfaces tension and stiffnessDistance, displacement and amplitudePotential difference and EMFDecay constant and frequency

What is the difference between units and dimensions of physical quantity?

Lets start from dimension to unit.[THERE ARE SEVEN BASIC FUNDAMENTAL DIMENSION AND ALL OTHER ARE MADE USING THESE COZ EVERYTHING DEPEND UPON THESE THING EITHER DIRECTLY OR INVERSLY]Dimension is basically all the fundamental required quantity in something.we see how these are related with each other(directly or inversly)for exampleforce=mass×accelerationf=m×af=m×v/tthis is the dimention of force(for reason refer to the starting bracket point)And when all this (RHS)is assumed to be unity then LHS gets a value and that is considered to be UNIT ,generally given a name after the scientist who worked for that like pressure has pascal as unit.