Complete List of Important Dimensionless Quantities

Complete List of Important Dimensionless Quantities (UPSC/SSC/RRB/JEE/NEET Level)

Mathematical Quantities

• Angle (Radian)
• Solid Angle (Steradian)
• Strain
• Poisson's Ratio
• Coefficient of Friction (μ)
• Relative Density (Specific Gravity)
• Refractive Index (n)
• Relative Permittivity (Dielectric Constant)
• Relative Permeability
• Magnification (Linear, Angular, Areal)
• Numerical Aperture
• Efficiency (η)
• Percentage
• Fraction
• Probability

Mechanics

• Coefficient of Restitution (e)
• Damping Ratio
• Drag Coefficient
• Lift Coefficient
• Reynolds Number
• Mach Number
• Froude Number
• Euler Number
• Weber Number
• Cauchy Number
• Strouhal Number
• Knudsen Number
• Aspect Ratio
• Shape Factor
• Slenderness Ratio
• Mechanical Advantage
• Velocity Ratio
• Gear Ratio
• Transmission Ratio

Fluid Mechanics

• Specific Gravity
• Relative Density
• Cavitation Number
• Pressure Coefficient
• Flow Coefficient
• Discharge Coefficient
• Coefficient of Velocity
• Coefficient of Contraction
• Coefficient of Resistance
• Loss Coefficient

Thermodynamics

• Coefficient of Performance (COP)
• Compressibility Factor (Z)
• Heat Capacity Ratio (γ = Cp/Cv)
• Prandtl Number
• Nusselt Number
• Grashof Number
• Rayleigh Number
• Stanton Number
• Biot Number
• Lewis Number
• Eckert Number
• Brinkman Number
• Jakob Number

Electromagnetism

• Relative Permittivity
• Relative Permeability
• Dielectric Constant
• Magnetic Susceptibility (SI)
• Relative Magnetic Susceptibility
• Coupling Coefficient
• Quality Factor (Q)
• Power Factor (cos φ)

Optics

• Refractive Index
• Magnification
• Resolving Power (often treated as dimensionless depending on definition)
• Numerical Aperture
• Reflectance
• Transmittance
• Absorptance
• Emissivity

Quantum Physics

• Spin Quantum Number
• Principal Quantum Number
• Azimuthal Quantum Number
• Magnetic Quantum Number
• Pauli Exclusion Numbers
• Occupation Probability

Nuclear & Atomic Physics

• Binding Energy per Nucleon (when normalized appropriately)
• Relative Atomic Mass
• Relative Molecular Mass
• Mass Number (A)
• Atomic Number (Z)
• Neutron Excess

Astronomy & Cosmology

• Redshift (z)
• Density Parameter (Ω)
• Hubble Parameter Normalized Form (h)

Chemistry-related (Used in Physics)

• Mole Fraction
• Activity Coefficient
• Equilibrium Constant
• pH
• pOH
• Degree of Dissociation
• Relative Humidity

Frequently Asked Dimensionless Quantities in Competitive Exams