Electric Welding MCQ PDF

21. Projection welding can be considered as a mass production form of

(a) seam welding.
(b) spot welding.
(c) upset welding.
(d) flash welding.

22. In comparison to spot welding, projection welding has the advantage(s) of

(a) simple welding process, more output and good finished appearance.
(b) electrode life is increased owing to use of low current density and low pressure.
(c) it is easy to weld certain parts which cannot be welded by spot welding .
(d) all of the above.

23. In seam welding

(a) the workpiece is fixed and disc electrodes move.
(b) the workpiece moves but rotating electodes are fixed.
(c) the electrodes used are of disc or roller shape.
(d) either (a) or (b) and (c).

24. In case of seam welding, the flow of current through the electrode should be

(a) intermittent.
(b) continuous.
(c) either (a) or (b).

25. In ……… welding it is essential that the surfaces to be welded are clean, dust and dirt free.

(a) butt
(b) spot
(c) seam
(d) both spot and seam

26. Seam welding is normally not recommended for

(a) aluminum alloys.
(b) stainless and coated steels.
(c) copper and high copper alloys.
(d) alloys of nickel and magnesium.

27. In percussion welding

(a) the process used depends on the arc effect for heating and not on the resistance.
(b) the action of process is so rapid that there is little heating effect in the material adjacent to the weld.
(c) the equipment used is quite expensive.
(d) all of the above.

28. The basic electrical requirement in arc welding is that there should be

(a) high open-circuit voltage.
(b) no arc blow.
(c) dc power supply.
(d) coated electrodes.

29. In arc welding, the temperature of the arc produced is of the order of

(a) 1,000°C
(b) 3,500 – 4,000°C
(c) 5,000 – 7,500°C
(d) 7,500 – 10,000°C

30. The electric arc has

(a) linear resistance characteristic.
(b) positive resistance characteristic.
(c) negative resistance characteristic.
(d) highly inductive characteristic.

31. In an electric arc welding, the voltage required to strike dc arc is about

(a) 50 – 60 V
(b) 80 – 90 V
(c) 100 – 120 V
(d) 220 V

32. In an electric arc welding, the voltage required to strike an ac arc is about

(a) 50 – 60 V
(b) 80 – 90 V
(c) 100 – 120 V
(d) 230 V

33. In an electric arc welding, the voltage required to maintain the arc will be

(a) 250 – 500 V
(b) 150 – 250 V
(c) 20 – 30 V
(d) below 10 V

34. For an electric arc welding the current range is usually

(a) 50 – 1,000 A
(b) 30 – 50 A
(c) 20 – 30 A
(d) below 20 A

35. Increased heat due to shorter arc is harmful owing to

(a) burn through.
(b) excessive porosity.
(c) undercutting of base material.
(d) all of the above.

35. Arc blow results in

(a) non-uniform weld beads.
(b) shallow weld puddle giving rise to weak weld.
(c) splashing out of metal from weld puddle.
(d) all of the above defects.

36. Arc blow effects occurring with dc welding machines can be reduced by

(a) shortening the arc column length.
(b) reducing the welding current or electrode size or rate of travel of the electrode.
(c) wrapping the welding electrode cable a few turns around the work.
(d) all of the above.

37. In an electric welding, major personal hazards are

(a) weld spatter.
(b) flying sparks.
(c) harmful infrared and ultraviolet rays from the arc.
(d) all of the above.

38. During electric arc welding as the thickness of the metal to be welded increases

(a) voltage is increased keeping current the same.
(b) current is increased keeping voltage unchanged.
(c) current and voltage, both are increased.
(d) current and voltage, both are reduced.

39. In a dc arc welding

(a) both electrode as well as workpiece are made +ve
(b) both electode as well as workpiece arc made -ve.
(c) electrode is made -ve and workpiece +ve.
(d) electrode is made +ve and workpiece -ve.

40. The length of arc required depends on

(a) kind of electrodes used, its coating and its diameter.
(b) magnitude of current used.
(c) position of welding.
(d) all of the above.