Basic Electrical interview Questions & Answers

1.What  is  electricity ?

Ans : Electricity is a general term used for all phenomena caused by electric charge whether static or in motion.

2.What are the types of electricity ?

Ans : There are two types,(1) static Electricity and (2) Current Electricity.

3.What is static electricity ?

Ans : Static electricity means electricity at rest in contradistinction to dynamic or current electricity the effects of which are purely due to the electrostatic field produced by the charge. As it is obtained by rubbing two substance such as glass and silk it is also called frictional electricity.

4.What is current electricity ?

Ans : Current electricity means the electricity in motion the effects of which are due to the flow of electrons in a conductor.

5.What are the types of current electricity ?

Ans : There are two types :- (1) Direct current and (2) Alternating current.

6.What are the different methods of producing electricity ? Give examples.

Ans : The methods are –
i) By means of frictions- Static electricity is produced.
ii) By means of chemical action in cells and batteries.
iii) By means of mechanical driving- Generator produces electricity in two dissimilar methods.
iv) By means of heat – Thermal electricity is produced.
v) By means of lighting effect – Electricity is produced in photo electric cell.

7.What are the sources of electricity ?

Ans : (1)Battery, (2) Generator and (3) Thermocouple.

8.What are the applications of electricity ?

Ans : Heating, Lighting, Welding, Running of Motors, Battery charging, Electroplating, Relays, telephones, Electronic Equipment, etc.

9.What are the effects of electricity ?

Ans : (1) Physiological effect (Electric shock), (2)Heating effect (Lamp, Heater, Fuse), (3)Magnetic effect (Fan, Motor, Electric bell), (4) Chemical effect (Battery charging and Electroplating) and (5) X – Ray effect ( X- Rays).

10.What are A.C. and D.C. ?

Ans : A.C is the abbreviation of an alternating current which flows to and from in a circuit in alternate direction periodically with the variation of its magnitude in regular manner that after reaching a maximum in one direction decreases to zero, finally reversing and reaching a maximum in the opposite direction decreases to zero again the cycle of pulsation being repeated continuously. D.C. is the abbreviation of a direct current which flows in one direction only and which does not have any appreciable pulsation in its magnitude.

11.Where is D.C. used ?

Ans : (1) Battery charging, (2)Electroplating, (3)Electrolysis, (4) Relays, (5) traction motors, (6) Cinema projector.

12. Where is A.C. used ?

Ans : (1) House hold appliances, (2) Fan, (3) Refrigerators, (4)Power driving motors. (5)Radio and T.V. Set etc.

13. How will you judge whether the supply is A.C. or D.C. in premises ?

Ans : By seeing fan and tube light connection.

14.What are conductors ?

Ans : Conductors are those metallic substances which have a large number of free electrons and offer a little resistance to the flow of electricity through them.

15. What are insulators ?

Ans : Insulators are those nonmetallic substances which have comparatively very few free electrons and offer enormous resistance that they do not practically allow electricity to flow through them.

16. What materials are generally used as conductors ?

Ans : Copper, Aluminum, Brass, Iron, Phosphor Bronze, Silver, Zinc, Tungsten, Nickel, etc.

17. What materials are generally used as insulators ?

Ans : Mica, Oil impregnated paper, Vulcanized rubber, Glass, Bakelite, Porcelain, Varnished Cotton, Wood etc.

18.What term is used for comparing the insulation materials ?

Ans : “Dielectric Strength”.

19. What is “Dielectric strength”?

Ans : Dielectric strength is the maximum kilovolts per millimeter which an insulating medium can withstand without breakdown.

20. What are the factors on which the dielectric strength depends ?

Ans : The dielectric strength depends on the following factors – i. Thickness of the specimen,
ii. Size and shape of electrodes used in applying stress,
iii. Form or distribution of the field of electric stress in the material,
iv. Frequency of the applied voltage,
v. Rate and duration of voltage application,
vi. Fatigue with repeated voltage application,
vii. Temperature,
viii. Moisture content and
ix. Possible chemical changes under stress.

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