31. During carbon arc welding if electrode is connected to positive
(a) are will be dull
(b) arc will not strike
(c) metal will not strike
(d) carbon will have a tendency to go into the weld joint
32. In which of the following methods of welding the molten metal is poured for joining the metals?
(a) Thermit welding
(b) Gas welding
(c) TIG welding
(d) Arc welding
33. In atomic hydrogen welding, the electrode is made of
(a) carbon
(b) graphite
(c) tungsten
(d) mild steel
34. The porosity of welded joint may be caused by
(a) low welding current
(b) incorrect size of electrodes
(c) poor base metal
(d) any of the above
35. In electrical resistance welding, the greatest resistance is offered by which of the following?
(a) Metal surface
(b) Contact point of electrode with metal top
ac) Contact point of an electrode with a metal bottom
(d) Contact layer of metals to be welded
36. The tips of the electrodes, for spot welding, are made of
(a) copper alloy
(b) porcelain
(c) mica
(d) carbon
37. During spot welding, the current flows for
(a) fraction of a minute to several minutes
(b) fraction of a second to several seconds
(c) few milliseconds
(d) few microseconds
38. ………………… welding is not a resistance welding process.
(a) Projection
(b) Seam
(c) Flush
(d) Carbon arc
39. The power factor of a spot welding machine is expected to be around
(a) Unity
(b) 0.8 lagging
(c) 0.3 to 0.5 lagging
(d) 0.8 leading
40. Which of the following methods is normally not preferred for welding of chromium molybdenum steels?
(a) Oxyacetylene welding
(b) Resistance welding
(c) Thermit welding
(d) Submerged arc welding
41. The welding of aluminium alloy entails which of the following problems?
(a) High thermal conductivity-quick dissipating heat
(b) On melting becomes thin liquid-tendency to run off
(c) Low specific resistance requiring heavy current
(d) All of the above
42. During carbon arc welding
(a) electrodes is connected to neutral if A.C. is used
(b) electrode is not connected to any voltage source when A.C. is used
(c) electrode is negative with respect to the work if D.C. is used
(d) electrode is positive with respect to the work if D.C. is used
43. In welding weld spatter defect is generally the result of
(a) too high voltage during welding
(b) too high current during welding
(c) low voltage during welding
(d) low current during welding
44. Arc blow (a welding defect) is generally encountered in
(a) arc welding using A.C. current
(b) arc welding using D.C. current
(c) thermit welding
(d) gas welding
45. Steel pipes are manufactured by
(a) argon arc welding
(b) thermit welding
(c) resistance welding
(d) arc welding