42 TOP CUR­RENT ELEC­TRIC­ITY ONE LINER NOTES

42 TOP CUR­RENT ELEC­TRIC­ITY ONE LINER NOTES

For all Electrical engineering exam.

1. The S.I. unit of power is watt

2. Elec­tric pres­sure is also called volt­age

3. The sub­stances which have a large num­ber of free elec­trons and of­fer a low re­sis­tance are called con­duc­tors

4. CI, CARBON, TUNGSTEN is  a poor con­duc­tor.

5. Pa­per is an in­su­lat­ing ma­te­r­ial.

6. The prop­erty of a con­duc­tor due to which it passes cur­rent is called con­duc­tance.

7. Con­duc­tance is rec­i­p­ro­cal of re­sis­tance.

8. The re­sis­tance of a con­duc­tor varies in­versely as area of cross-sec­tion.

9. With rise in tem­per­a­ture the re­sis­tance of pure met­als in­creases.

10. With rise in tem­per­a­ture the re­sis­tance of semi-con­duc­tors de­creases.

11. An in­stru­ment which de­tects elec­tric cur­rent is known as gal­vanome­ter.

12. Man­ganin ma­te­r­ial has nearly zero tem­per­a­ture co-ef­fi­cient of re­sis­tance.

13. Power are ad­di­tive is true both for a se­ries and a par­al­lel D.C. cir­cuit.

14. Car­bon ma­te­ri­als has a neg­a­tive tem­per­a­ture co-ef­fi­cient of re­sis­tance.

15. Ohm’s law is not ap­plic­a­ble to
vac­uum tubes.

16. Which is the best con­duc­tor of elec­tric­ity ?
(a) Iron
(b) Sil­ver
(c) Cop­per
(d) Car­bon 

Ans: b

17. A re­sis­tance hav­ing rat­ing 10 ohms, 10 W is likely to be a wire wound re­sis­tor.

18. Varis­tors are non-lin­ear re­sis­tors.

19. In­su­lat­ing ma­te­ri­als have the func­tion of pre­vent­ing an open cir­cuit be­tween the volt­age source and the load.

20. The rat­ing of a fuse wire is al­ways ex­pressed in am­peres.

21. The min­i­mum charge on an ion is equal to the charge of an elec­tron.

22. In a se­ries cir­cuit with un­equal re­sis­tances the high­est re­sis­tance has the high­est volt­age drop.

23. The fil­a­ment of an elec­tric bulb is made of tung­sten.

24. The re­sis­tance of a few me­ters of wire con­duc­tor in closed elec­tri­cal cir­cuit is
prac­ti­cally zero.

25. If a par­al­lel cir­cuit is opened in the main line, the cur­rent is zero in all branches.

26. A closed switch has a re­sis­tance of zero.

27. The in­su­la­tion on a cur­rent car­ry­ing con­duc­tor is pro­vided.

(a) to pre­vent leak­age of cur­rent
(b) to pre­vent shock
(c) both of above fac­tors.

28. The thick­ness of in­su­la­tion pro­vided on the con­duc­tor de­pends on  the mag­ni­tude of volt­age on the con­duc­tor.

29. Cur­rent quan­ti­ties re­main the same in all parts of a se­ries cir­cuit.

30. An elec­tric fil­a­ment bulb can be worked from

(a) D.C. sup­ply only
(b) A.C. sup­ply only
(c) Bat­tery sup­ply only
(d) All above .

Ans: d.

31. Elec­tric cur­rent pass­ing through the cir­cuit pro­duces ther­mal ef­fect.

32. A glass rod when rubbed with silk cloth is charged be­cause it gives away elec­trons.

33. Whether cir­cuit may be AC. or D.C. one, fol­low­ing is most ef­fec­tive in re­duc­ing the mag­ni­tude of the cur­rent Re­sis­tor.

34. It be­comes more dif­fi­cult to re­move third elec­tron from the or­bit.

35. In the case of di­rect cur­rent
mag­ni­tude and di­rec­tion of cur­rent re­mains con­stant.

36. Bulbs in street light­ing are all con­nected in par­al­lel.

37. For test­ing ap­pli­ances, the wattage of test lamp should be high.

38. Spark­ing oc­curs when a load is switched off be­cause the cir­cuit has high in­duc­tance.

39. A field of force can ex­ist only be­tween two ions.

40. A sub­stance whose mol­e­cules con­sist of dis­sim­i­lar atoms is called com­pound.

41. In­ter­na­tional ohm is de­fined in terms of the re­sis­tance of a col­umn of mer­cury.

42. Wheat­stone bridge method can be used for ab­solute mea­sure­ment of re­sis­tances.