One Liner about Passive elements for RRB JE

 Passive elements are those which require external energy sources for their operation. Resistors, inductors and capacitors are examples of few passive elements. In this article one liner on passive elements will be discussed which are frequently asked in RRB JE exams.

1. Carbon Resistors are used in electric and electronic Circuits and equipments for power controlling and over current protection for low power rating (quarter, half and one watts). 

2. Wire wound resistors are used for earth fault protection, motor starting over current protection and high Wattage motor speed controlling.

3. Unit of resistance is ohm or volt per ampere.

4. Reciprocal of resistance is conductance and unit of conductance is Mho or Siemens.

5. Resistors are power dissipative elements means they convert excess power into heat energy to limit the power.

6. The total opposition offered to the flow of current in AC circuit is called Impedance.

7. Power Factor of purely resistive load is Unity.

8. Resistance is directly proportional to length and reversely proportional to area.

9. Inductor is a conductor wire wound in the form of a coil. 

10. Inductance unit is Henry. 

11. Inductor is used in windings of motors, Transformers, induction base equipments etc. 

12. Coil wound on a iron core train wali gadi maximum Inductance( Mili Henry)  and wound on air core has minimum Inductance (Micro Henry). 

13. Iron core inductor operates on low frequency where as air core and ferrite core inductors operate on higher frequencies.

14. Inductor is a charge storing element which stores charge in form of magnetic energy.

15. Inductors are made of insulated copper wires.

16. Resistance offered by an inductor is called reluctance and unit of reluctance is ampere-turn/weber.

17. Reluctance is also directly proportional to length of inductor and reversely proportional to area.

18. Two conductor plates separated by a insulating dielectric material forms a capacitor.

19. Capacitor stores charge in the form of electrostatic energy in electric field.

20. Unit of capacitor is Farad, Microfarad, Picofarad etc.

21. Electrolytic Capacitors (Unipolar) have  value in Microfarad range and used in voltage sources.

22. Ceramic capacitors (Bipolar) have value in Picofarad range and used in filter circuits.

23. Paper capacitors have value in milifarad range are used in  single phase AC motors to split the phase to provide starting torque.

24. In resistors voltage and current remain same phase, in inductors current lags voltage by 90° and in capacitor voltage lags current by 90°.

25. The reciprocal of resistance is Conductance.

26. The reciprocal of Reluctance is Permeance.

27. The reciprocal of impedance is admittance.

28. The reciprocal Reactance is Susceptance.

29. The reciprocal of capacitance is elastance.

30. All the loads are indutive in nature so they have lagging power factor. To improve the power Factor, Capacitor banks are used which reduces phase difference between voltage and current.

Author:- Amarjeet Singh Jamwal authored articles on Basic Electronics Engineering, Electric Traction, and Electronics Practical for INFO4EEE Website