MOST IMPORTANT DIMENSIONS OF QUANTITIES

MOST IMPORTANT DIMENSIONS OF QUANTITIES USED IN ELECTRCAL ENGINEERING :- 

Units can be represented dimensionally in terms of units of length L, mass M,

time T and current l. 

The dimensions can be derived as under :

1. Velocity = length/time = L/T = LT–1

2. Acceleration = velocity/time = LT–1/T = LT–2

3. Force = mass × acceleration = MLT–2

4. Charge (coulomb) = current × time = I

5. Work or energy = force × distance = ML2T–2

6. EMF or potential = work/charge

= ML2T–2/IT = ML2I–1T–3

7. Power = work/time = ML2T–2/T = ML2T–3

8. Current density = current/area = I/L2 = IL–2

9. Resistance = emf/current = ML2I–1T–3/I = ML2I–2T–3

10. Electric flux density = electric flux or charge/area =IT/L2 = ITL2

11. MMF = current × number of turns = I

12. Conductance = I/resistance = I/ML2I–2T–3 = I2T3M–1L–2

13. Electric field intensity = volt/metre = ML2I–1T–3/L = MLI–1T–3

14. Resistivity =

resistant area

length

×

= (ML2I–2T–3)(L2)/L

= ML3I–2T–3

15. Magnetic field intensity (H) = MMF/length

= I/L = IL–1

16. Magnetic flux = emf × time = (ML2I–1T–3) (T) = ML2I–1T–2

17. Magnetic flux intensity = magnetic flux/area

= (ML2I–1T–2)/L2 = MI–1T–2

18. Impedance = emf/current = ML2I–1T–3

19. Admittance = I/impendence = I2T3M–1L–2

20. Inductance = magnetic flux/current

= ML2T–2I–1/I = ML2T–2I–2

21. Capacitance = electric charge/potential

= IT/ML2T–3l–1 = M–1L–2T4l2