APPENDIX. 



DIMENSIONS OF PHYSICAL QUANTITIES. 



L — length ; M = mass ; T ^ time. 



Quantity. 

 Area. 

 Volume. 

 Mass. 

 Density. 

 Velocity. 

 Acceleration 



Dimensions 

 [L-] 

 [L«] 

 [M] 



[M L-8] 

 [L T-i] 

 [LT-2] 

 [o]_ 

 Angular Velocity. [T"^] 



Angle. 



Quantity. 

 Momentum. 

 Moment of Inertia. 

 Force. 



Stress (per unit area). 

 Work or Energy. 

 Rate of Working (Power). 

 Heat. 

 Thermal Conductivity. 



In Electrostatics. 



Quantity of Electricity. 



SurfaceDensity: quantity per unit area. 



Difference of Potential: quantity of work required 

 to move a quantity of electricity ; (work done) -^ (quan- 

 tity moved). 



Electric Force, or Electro-motive Intensity: 

 (quantity) -^ (distance-). 



Capacity of an accumulator : e -^ E. 



Specific Inductive Capacity. 



In Magnetics. 

 Quantity of Magnetism, or Strength of Pole. 

 Strength or Intensity of Field: 



(quantity) -^ (distance^). 

 Magnetic Force. 



Magnetic Moment: (quantity) X (length). 

 Intensity of Magnetization: magnetic moment per 



unit volume. 

 Magnetic Potential: work done in moving a quantity 



of magnetism ; (work done) -f- (quantity moved). 

 Magnetic Inductive Capacity. 



In Electro-magnetics. Symbol. 



I n tensity of Current. i 



Quantity of Electricity conveyed by current : e 



(intensity) X (time). 

 Potential, or difference of potential: (work E 



done) -^ (quantity of electricity upon which 



work is done). 

 Electric Force: the mechanical force act- E 



ing on electro-magnetic unit of quantity ; 



(mechanical force) -h- (quantity). 

 Resistance of a conductor : E-r-i- ^ 



Capacity: quantity of electricity stored up q 



per unit potential-difference produced by it. 

 Specific Conductivity: the intensity of 



current passing across unit area under the 



action of unit electric force. 

 Specific Resistance: the reciprocal of r 



specific conductivity. 



Symbol. 



c 

 a 

 E 



Dimensions. 

 [L M T-i] 

 [M L-^J 

 [L M T--^] 

 [L-i M T-'^] 

 [L-^ M T-2] 

 [L'^ M T-''] 

 [L-^ M T-^] 

 LL-i M T-i] 



Dimensions in 

 electrostatic system. 



[lHi^ t-1] 



[L-i Mi T-i] 

 [L* Mi T-i] 



[L-i Mi T-i] 



Cor ^ 



k 



[L] 



[o] 



VoxCl [LiMiT-i] 



Dimensions in 



electro-magnetic 



system. 



[Li M* T-i] 



[Li Mi] 



\U Mi T-^] 

 [Li Mi T-2] 



[LT-i] 

 [L-i T^] 



[L--= T] 



[o] 



Name of 

 practical unit. 



Ampere. 

 Coulomb. 



Volt. 



Ohm. 

 Farad. 



[L2 1-1] 



Smithsonian Tables. 



175 



