Electrical Power Engineering Multiple Choice Questions and Answers (MCQs) Part 6:

252. The atomic hydrogen welding is based on the principle(s) of

(a) obtaining atomic hydrogen by means of an electric arc be­tween two tungsten electrodes, in an atmosphere of hydro­gen at atmospheric pressure.
(b) development of very high temperature by recombination of atoms which occurs in the cooler regions immediately out­side the arc.
(c) very large heat conductivity of hydrogen at high tempera­ture.
(d) all of the above.

Answer : (d) all of the above.


253. In atomic hydrogen arc welding

(a) an arc is maintained between two tungsten electrodes.
(b) a stream of hydrogen gas under a pressure of 0.5 kg/cm2 is passed through the arc and around the electrodes.
(c) ac supply is used.
(d) all of the above.

Answer : (d) all of the above.


254. In atomic hydrogen welding, electrodes are of long life. It is be­cause

(a) of being non-pressure process.
(b) of arc being in the shape of a fan.
(c) of ac supply.
(d) two arcs are used at a time.

Answer : (c) of ac supply.


255. Helium produces

(a) faster welding speeds.
(b) deep penetration.
(c) narrower heat affected zone in base metal.
(d) all of the above.

Answer : (d) all of the above.


256. In argon arc welding, argon is used as

(a) an agent for heat transfer.
(b) a shield to protect the work from oxidation.
(c) a source of heat.
(d) a flux.

Answer : (b) a shield to protect the work from oxidation.


257. In argon arc welding, the argon is used to

(a) prevent oxidation of metal by coming in contact with air.
(b) create inert atmosphere around the work.
(c) obviate the necessity for using flux.
(d) all of the above.

Answer : (d) all of the above.


258. Submerged arc process is characterized by

(a) high welding current.
(b) exceptionally smooth heads.
(c) deep penetration.
(d) all of the above.

Answer : (d) all of the above.


259. Electrode is not consumed in case of

(a) TIG welding.
(b) atomic hydrogen arc welding.
(c) MIG welding.
(d) all of the above.

Answer : (a) TIG welding.


260. Unlike TIG welding, MIG welding

(a) needs no post-weld cleansing.
(b) needs no flux.
(c) uses consumable electrodes.
(d) provides complete protection from atmospheric contamina­tion.

Answer : (c) uses consumable electrodes.


261. MIG welding is becoming more and more popular as it

(a) is easy in operation.
(b) has high metal deposit rate.
(c) both (a) and (b).
(d) can be used for both ferrous and nonferrous metals.

Answer : (c) both (a) and (b).


262. In MAG (metal active gas) welding the gas used is

(a) argon or helium.
(b) carbon dioxide or its mixture with other gas.
(c) hydrogen.
(d) any of the above.

Answer : (b) carbon dioxide or its mixture with other gas.


263. A weld bead of wineglass design is produced in

(a) plasma arc welding.
(b) MAG welding.
(c) electron beam welding.
(d) all of the above.

Answer : (a) plasma arc welding.


264. In electro-slag welding, theoretically there is no limit to the

(a) rate of metal deposit.
(b) thickness of weld bead.
(c) temperature of salt bath.
(d) rate of slag consumption.

Answer : (b) thickness of weld bead.


265. In manual arc welding of mild steel, the metal deposition rate will be about

(a) 10-15 kg per hour.
(b) 5-10 kg per hour.
(c) 2-5 kg per hour.
(d) below 1 kg per hour.

Answer : (c) 2-5 kg per hour.


266. In ultrasonic welding, the frequency range is usually

(a) 20-60 kHz
(b) 50-100 kHz
(c) 100-200 kHz
(d) above 250 kHz

Answer : (a) 20-60 kHz


267. Welding is not done directly from the supply mains as

(a) its voltage is too high.
(b) it is impracticable to draw heavy currents directly from the supply mains.
(c) its voltage remains fluctuating.
(d) none of the above.

Answer : (b) it is impracticable to draw heavy currents directly from the supply mains.


268. AC welding machine cannot be used for

(a) resistance welding.
(b) submerged arc welding.
(c) MIG welding.
(d) atomic hydrogen welding.

Answer : (c) MIG welding.


269. In electric welding, arc blow can be avoided by

(a) using ac machines.
(b) increasing arc length.
(c) using bare electrodes.
(d) welding away from ground connections.

Answer : (a) using ac machines.


270. Welding leads have

(a) high current carrying capacity.
(b) high flexibility.
(c) both (a) and (b).
(d) none of the above.

Answer : (c) both (a) and (b).


271. The welding load

(a) is always intermittent.
(b) is always continuous and constant.
(c) is always continuous but varying.
(d) may be any one of the above.

Answer : (a) is always intermittent.


272. The load power factor using welding transformer depends on

(a) arc length.
(b) material to be welded.
(c) type of electrode to be used.
(d) all of the above.

Answer : (b) material to be welded.


273. For power factor correction in a welding circuit, a capacitor is usually connected

(a) across the mains.
(b) across secondary side of welding transformer.
(c) across primary side of welding transformer.
(d) across arcing electrodes.

Answer : (c) across primary side of welding transformer.


274. Which of the following is different from the remaining ?

(a) Bun welding.
(b) Elector-slag welding.
(c) TIG welding.
(d) MIG welding.

Answer : (a) Bun welding.


275. Chipping hammers are used

(a) for slag welding.
(b) for aligning the pieces to be welded.
(c) for removing slag from welding.
(d) for marking spots to be welded.

Answer : (c) for removing slag from welding.


276. The danger of electric shock is maximum

(a) before welding.
(b) during arcing.
(c) while inserting electrode into the holder.
(d) after welding.

Answer : (c) while inserting electrode into the holder.


277. The eyes of welding operator must be protected against

(a) infrared radiations.
(b) ultraviolet radiations.
(c) both (a) and (b).
(d) solar radiations.

Answer : (c) both (a) and (b).


278. Which of the following automatic welding processes is likely to give maximum rate of metal deposition ?

(a) Multiple power submerged arc.
(b) Gas shielded bare wire.
(c) Single wire submerged arc.
(d) Continuous flux covered electrode.

Answer : (a) Multiple power submerged arc.


279. In a welded joint poor fusion is on account of

(a) improper current.
(b) high welding speed.
(c) uncleaned metal surface.
(d) lack of flux.

Answer : (a) improper current.


280. Which of the following uses consumable electrodes?

(a) TIG.
(b) MIG.
(c) laser.
(d) None of the above.

Answer : (b) MIG.


281. In which of the following welding methods the molten metal is poured for joining the metals?

(a) Gas welding.
(b) Thermit welding.
(c) TIG welding.
(d) Arc welding.

Answer : (b) Thermit welding.


282. The porosity of weld joint may be caused by

(a) poor base metal.
(b) incorrect size of electrode.
(c) low welding current.
(d) any of the above.

Answer : (a) poor base metal.


283. In welding, weld spatter defect is generally because of too …………. during welding.

(a) high voltage
(b) high current
(c) low voltage
(d) low current

Answer : (b) high current


284. High temperature metals, such as columbium can be easily welded by

(a) MIG welding.
(b) TIG welding.
(c) electron beam welding.
(d) flash butt welding.

Answer : (c) electron beam welding.


285. …………. welding is used for welding of car body.

(a) Gas
(b) Spot
(c) Carbon-arc
(d) Atomic hydrogen

Answer : (b) Spot


286. Grey iron is usually welded by

(a) gas welding.
(b) resistance welding.
(c) TIG welding.
(d) arc welding.

Answer : (a) gas welding.


287. The method recommended for the welding of aluminium alloy is …………. welding.

(a) dc arc
(b) ac arc
(c) acetylene-oxygen gas
(d) tungsten arc

Answer : (d) tungsten arc


288. Steel pipes are manufactured by

(a) arc welding.
(b) argon arc welding.
(c) resistance welding.
(d) thermit welding.

Answer : (c) resistance welding.


289. Steel rails are welded by

(a) thermit welding.
(b) argon arc welding.
(c) gas welding.
(d) resistance welding.

Answer : (a) thermit welding.


290. Aluminium is difficult to weld as

(a) it has an oxide coating.
(b) it conducts away heat very rapidly.
(c) both (a) and (b).
(d) none of the above.

Answer : (c) both (a) and (b).


291. Electronic components are joined by

(a) spot welding.
(b) soldering.
(c) brazing.
(d) none of the above.

Answer : (b) soldering.


292. Aircraft body is

(a) rivetted.
(b) seam welded.
(c) gas welded.
(d) spot welded.

Answer : (a) rivetted.


293. A seamless pipe has

(a) arc welded joint.
(b) spot welded joint.
(c) no joint.
(d) either (a) or (b).

Answer : (c) no joint.


294. The method usually not preferred for welding of chromium mo­lybdenum steel is

(a) thermit welding.
(b) resistance welding.
(c) submerged arc welding.
(d) oxyacetelyne gas welding.

Answer : (b) resistance welding.


295. Light

(a) is a form of heat energy.
(b) is a form of electrical energy.
(c) consists of electromagnetic waves.
(d) consists of shooting particles.

Answer : (c) consists of electromagnetic waves.


296. Radiant efficiency of the luminous source depends on

(a) temperature of the source.
(b) wavelength of light rays.
(c) shape of the source.
(d) all of the above.

Answer : (a) temperature of the source.


297. A substance which changes its electrical resistance when illumi­nated by light is called

(a) photoconductive.
(b) photovoltaic.
(c) photoelectric.
(d) none of the above.

Answer : (a) photoconductive.


298. Materials which reflect all wavelength in the spectrum of light appear to be

(a) opaque.
(b) transparent.
(c) black to white.
(d) green to red.

Answer : (c) black to white.


299. An object, which appears red to the eyes, absorbs

(a) blue radiations.
(b) violet radiations.
(c) green radiations.
(d) all of the above.

Answer : (d) all of the above.


300. The sensors in the eye are known as

(a) retina and antenna.
(b) wires and nerves.
(c) rodes and cones.
(d) none of the above.

Answer : (c) rodes and cones.


301. The colour temperature of daylight is about

(a) 100 K
(b) 200 K
(c) 500 K
(d) 600 K

Answer : (d) 600 K

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