Basic Electrical Interview Questions and Answers:
- What is the difference between fuse and circuit breaker? Fuse:-
A fuse has a wire that melts in the heat of a short circuit or high current and breaks the circuit. Once melted, you must replace it. Circuit breaker:-
A circuit breaker interrupts the current without melting (a pair of metal sheets with different coefficient of thermal expansion, for example) and can be reset.
- What about solar electricity? An electrical contractor can install solar panels on his property. The excess energy collected by your solar panels is fed into the electrical grid. Receive credit for generated energy on your electricity bill.
- What is electricity? Electricity is a general term used for all phenomena caused by electrical charges, whether static or moving.
- What are the types of electricity? There are two kinds
(1) Static electricity and
(2) Current electricity.
- What is static electricity? Static electricity refers to electricity at rest, as opposed to dynamic or current electricity, whose effects are exclusively due to the electrostatic field produced by the charge. Since it is obtained by rubbing two substances like glass and silk together, it is also called frictional electricity.
- What is current electricity? By current electricity we mean electricity in motion whose effects are due to the flow of electrons in a conductor.
- What are the current types of electricity? There are two kinds :-
(1) Direct current and
(2) Alternating current.
- What are the different methods of electricity production? Give examples. The methods are:
i) Through friction- Static electricity is produced.
ii) Through chemical action in cells and batteries.
iii) By means of mechanical conduction- The generator produces electricity in two different methods.
iv) Through heat – Thermal electricity is produced.
v) Through light effect – Electricity is produced in the photoelectric cell.
- What are the sources of electricity? (1) Battery,
(2) Generator and
- What are the applications of electricity? Heating, Lighting, Welding, Engine Operation, Battery Charging, Electroplating, Relays, Telephones, Electronic Equipment, etc.
- What are the effects of electricity? (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-ray).
- What are A.C. and D.C.? AC is the abbreviation of an alternating current that flows to and from a circuit in an alternating direction periodically with the variation of its magnitude in a regular way that after reaching a maximum in one direction decreases to zero, finally inverting and reaching a maximum in the opposite . direction decreases to zero again the pulse cycle repeats continuously. D.C. is the abbreviation of a direct current that flows in only one direction and that does not have any appreciable pulsation in its magnitude.
- Where is DC used? (1) battery charge,
(5) traction motors,
(6) Movie projector.
- Where is A.C. used? (1) Household appliances,
(4) Power drive motors.
(5) Radio and television equipment, etc.
- How will you judge if the supply is A.C. or D.C. on site? Seeing the fan connection and tube light.
- What are drivers? Conductors are those metallic substances that have a large number of free electrons and offer little resistance to the flow of electricity through them.
- What are insulators? Insulators are those non-metallic substances that have comparatively very few free electrons and offer enormous resistance that practically does not allow electricity to flow through them.
- What materials are generally used as conductors? Copper, Aluminum, Brass, Iron, Phosphor Bronze, Silver, Zinc, Tungsten, Nickel, etc.
- What materials are generally used as insulators? Mica, oil impregnated paper, vulcanized rubber, glass, Bakelite, porcelain, varnished cotton, wood, etc.
- What term is used to compare insulation materials? “Dielectric strength”.
- What is “dielectric strength”? Dielectric strength is the maximum kilovolt per millimeter that an insulating medium can withstand without breaking.
- What are the factors on which the dielectric strength depends? Dielectric strength depends on the following factors:
I. Thickness of the sample,
ii. Size and shape of the electrodes used to apply voltage.
iii. Shape or distribution of the electrical stress field in the material,
iv. Frequency of applied voltage,
v. Rate and duration of voltage application,
saw. Fatigue with repeated application of voltage,
viii. Moisture content and
ix. Possible chemical changes under stress.