## Conversion factor

#### Conversion of length

• 1 centimetre = 10-2 metre
• 1 millimetre = 10-3metre
• 1 micrometre = 10-6metre
• 1 nanometre = 10-9 metre
• 1 angstrom= 10-10 metre
• 1 fermi = 10-15 metre
• 1 kilometre = 103 metre
• 1 austronomical unit = 1AU=1.496 × 1011 metre
• 1 light year = 1 ly = 9.461 ×1015metre
• 1 mile = 1.609 ×103 metre
• 1 yard = 0.9144 metre
• 1 inch = 0.0254 metre

#### Conversion of time

• 1 mili second= 10-3 second
• 1 micro second = 10-6 second
• 1 neno second = 10-9 second
• 1 hour = 60 minute = 3600 second
• 1 day = 24 hours =86400 second
• 1 year = 365 day = 3.156× 107 second
• 1 sec = 10-8second

#### Conversion of mass

• 1 gram = 10 -3 kg
• 1 quintal = 100 kg
• 1 tonne = 1000 kg
• 1 slug = 14.59 kg
• 1 Chandersekhar limit = 1.4 × mass of sun = 2.8 × 1030 kg
• 1 atomic mass unit = 1u = 1.66×10-10

## What is the dimensional formula ?

The dimensional formula of the physical quantity is an expression which shows how and which of the base quantities represent the dimensions of a physical quantity.

For example [ M0L2T0 ] is the dimensional formula of velocity. similarly, [ M0L3T0 ] is the dimensional formula of volume.

### Dimensional formula of all important physical quantities.

Dimensional formula of major physical quantities e.g. area, volume, velocity, acceleration, force, momentum, impulse, work, energy, power, surface tension etc. are following:

Physical quantity Dimensional formula
Acceleration M0L1T-2
Acceleration due to gravity M0L1T-2
Angle M0L0T0
Angular acceleration M0L0T-2
Angular displacement M0L0T0
Angular frequency M0L0T-1
Angular impulse M1L2T-1
Angular momentum M1L2T-1
Angular velocity M0L0T-1
Area M0L2T0
Binding energy of nucleus M1L2T-2
Boltzmann constant M1L2T-2K-1
Bulk modulus M-1L0T-2
Capacity M-1L-2T4A2
Capacitative reactance M1L2T-3A-2
Centripetal acceleration M0L1T-2
Charge M0L0T1A1
Coefficient of elasticity M1L-1T-2
Coefficient of mutual inductance M1L2T-2A-2
Coefficient of self inductance M1L2T-2A-2
Conductivity M-1L-2T3A2
Critical velocity M0L1T-1
Current density M0L-2T0A1
Decay constant M0L0T-1
Density M1L-3T0
Dielectric constant M0L0T0
Efficiency M0L0T0
Electrical resistivity M1L3T-3A-2
Electric current M0L0T0A1
Electric dipole moment M0L1T1A1
Electric field M1L1T-3A-1
Electric intensity M1L1T-3A-1
Electric potential M1L2T-3A-1
Electric permittivity of free space M-1L-3T4A2
Energy M1L2T-2
Energy density M1L-1T-2
Entropy M1L2T-2K-1
Escape speed M0L1T-1
Frequency M0L0T-1
Force M1L1T-2
Force constant M1L0T-2
Gas constant M1L2T-2K-1mol-1
Gravitational constant M-1L3T-2
Heat M1L2T-2
Heat capacity M1L2T-2K-1
Hubble constant M0L0T-1
Illuminance M1L0T-3
Illuminating power of source M1L2T-3
Impulse M1L1T-1
Inductance M1L2T-2A-2
Inductive reactance M1L2T-3A-3
Intensity of illumination M1L0T-3
Intensity of wave M1L0T-3
Internal energy M1L2T-2
Kinetic energy M1L2T-2
Kinematic viscosity M0L2T-1
Latent heat M0L2T-2
Linear mass density M1L-1T0
Luminance M1L0T-3
Luminous efficiency M0L0T0
Luminous flux M1L2T-3
Luminous intensity M1L2T-3
Luminous power M1L2T-3
Magnification M0L0T0
Magnetic dipole moment M0L2T0A1
Magnetic induction M1T-2A-1
Magnetic intensity A1L-1
Magnetic field M1L0T-2A-1
Magnetic field strength M0L-1T0A1
Magnetic flux M1L2T-2A-1
Magnetic permeability of free space M1L1T-2A-2
Mass defect M1L0T0
Mechanical equivalent of heat M0L0T0
Moment of force M1L2T-2
Moment of inertia M1L2T0
Momentum M1L1T-1
Planck constant M1L2T-1
Pole strength M0L1T0A1
Potential energy M1L2T-2
Power M1L2T-3
Power of lens M0L-1T0
Pressure M1L-1T-2
Pressure energy M1L2T-2
Quality factor M0L0T0
Rate of flow M0L3T-1
Refractive index M0L0T0
Relative Luminosity M0L0T0
Resistance M1L2T-3A-2
Reasonant frequency M0L0T-1
Reynolds number M0L0T0
Rydberg constant M0L-1T0
Specific gravity M0L0T0
Specific heat M0L2T-2K-1
Specific resistance or resistivity M1L3T-3A-2
Specific volume M-1L3T0
Speed M0L1T-1
Stefn’s constant M1L0T-3K-4
Surface density of charge M0L-2T1A1
Surface potential M0L2T-2
Temperature M0L0T0A1
Thermal expansion coefficient M0L0K-1
Torque M1L2T-2
Trigonometric ratio M0L0T0
Velocity M0L1T-1
Velocity of light in vaccum M0L1T-1
Viscosity M1L-1T-1
Volume M0L3T0
Wave number M0L-1T0
Wien’s constant M0L1T0K1
Work M1L2T-2

## How many fundamental and supplementary units in SI?

In SI, there are seven base ( fundamental ) units and two supplementary units.

#### Base unit

Physical quantity Unit Symbol
Mass Kilogram kg
Length Metre m
Time Second s
Temperature Kelvin K
Electric current Ampere A
Luminous intensity Candela cd
Quantity of matter Mole mol

#### Supplementary units

Physical quantity Unit Symbol