Electric Welding MCQ PDF

41. Overhead welding position is thought to be the most

(a) hazardous.
(b) economical.
(c) useful.
(d) difficult.

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42. In arc welding best results are obtained when arc length is equal to

(a) 25 mm.
(b) 19 mm.
(c) diameter of electrode.
(d) double the diameter of the electrode.

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43. Flat position welding is considered to be the most

(a) easiest and economical.
(b) hazardous.
(c) adaptable for welding of both ferrous and non-ferrous metals particularly for cast iron.
(d) both (a) and (c).

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44. In direct current straight polarity (DCSP) or electrode negative welding

(a) heavily coated electrodes are used.
(b) base metal penetration is narrow and deep.
(c) electrode is the hottest.
(d) workpiece is relatively cooler.

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45. In direct current reverse polarity or electrode positive welding

(a) workpiece is the hottest.
(b) bare and medium coated electrodes can be used.
(c) electrode is the hottest.
(d) base metal penetration is narrow and deep.

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46. The electrode is coated in order to

(a) improve bead quality.
(b) cleanse the base metal.
(c) provide shielding to weld pool.
(d) prevent atmospheric contamination.

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47. In DCRP or electrode positive welding, the heat produced at the electrode is………of total heat produced.

(a) one-third.
(b) two-third.
(c) three-fourth.
(d) one-fourth.

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48. A 10 SWG electrode usually operates in the current range of

(a) 95 – 135 A
(b) 80 – 95 A
(c) 45 – 70 A
(d) 20 – 30 A

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49. Electrode of 8 SWG is to be employed for welding two 12.5 mm steel plates. The current required will of the order of

(a) 20 A
(b) 50 A
(c) 150 A
(d) 250 A

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50. The purpose of coating on arc welding electrodes is to

(a) provide a protective covering.
(b) provide slag for protection of the molten metal.
(c) stabilize the arc.
(d) all of the above.

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51. 20 per cent duty cycle of a welding machine means

(a) operation of machine for 2 minutes in a duration of 10 minutes.
(b) machine output is 20 per cent of rated output.
(c) machine operates at 20 per cent efficiency.
(d) operation of machine is for 1 minute in a duration of 5 minutes.

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52. In carbon arc welding, if the electrode is connected to the + ve terminal of the dc supply

(a) arc will not strike.
(b) arc will be dull.
(c) carbon arc will have tancdency to go in to the weld joint.
(d) metal will not melt.

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53. Carbon arc welding has the main drawback of

(a) occurrence of blow holes owing to magnetic arc blow especially while welding near edges of the workpiece.
(b) need of separate filler.
(c) necessity of bare electrodes.
(d) fast consumption of electrodes.

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54. Carbon arc welding

(a) uses carbon or graphite rod as a negative electrode and work to be welded as a positive.
(b) cannot be done with ac supply.
(c) is not suitable for vertical and overhead welding.
(d) all of the above.

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55. Carbon arc welding is suitable particularly for……..metals.

(a) ferrous.
(b) nonferrous.
(c) all.

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56. For metal arc welding

(a) both dc and ac can be used but ac is preferred.
(b) bare electrodes are no longer used except for automatic welding having arrangement to protect the weld area from the atmosphere.
(c) correct welding current, voltage and speed are very important.
(d) all of the above.

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57. 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 temperatures.
(d) all of the above.

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58. 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.

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59. 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.

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60. Helium produces

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

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