ELECTRIC WELDING | NCERTBOOKSPDF.COM

Objective Questions

Short notes

Objective questions (Answers are given below)

The basic electrical requirement in arc welding
is that there should be
(a) coated electrodes
(b) high open-circuit voltage
(c) no arc blow
(d) d.c. power supply.
Welding is not done directly from the
supply mains because
(a) it is customary to use welding machines
(b) its voltage is too high
(c) its voltage keeps fluctuating
(d) it is impracticable to draw heavy
currents.

A.C. welding machine cannot be used for welding
(a) MIG
(b) atomic hydrogen
(c) resistance
(d) submerged arc.
In electric welding, arc blow can be avoided
by
(a) using bare electrodes
(b) welding away from earth ground
connection
(c) using a.c. welding machines
(d) increasing arc length.

In DCSP welding
(a) electrode is the hottest
(b) workpiece is relatively coole
(c) base metal penetration is deep
(d) heavily-coated electrodes are used.
Overhead welding position is thought to be the
most
(a) hazardous
(b) difficult
(c) economical
(d) useful.
The ultimate aim of using electrode coating is
to
(a) provide shielding to weld pool
(b) prevent atmospheric contamination
(c) improve bead quality
(d) cleanse the base metal.
In electrode-positive welding ……….. of the
total heat is produced at the electrode.
(a) one-third
(b) two-third
(c) one-half
(d) one-fourth.
Submerged arc process is characterised by
(a) deep penetration
(b) high welding current
(c) exceptionally smooth beads
(d) all of the above.
The major disadvantage of carbon arc welding
is that
(a) there is occurrence of blow holes
(b) electrodes are consumed fast
(c) separate filler rod is needed
(d) bare electrodes are necessary.
In atomic hydrogen welding, electrodes are
long-lived because
(a) two are used at a time
(b) arc is in the shape of a fan
(c) of a.c. supply
(d) it is a non-pressure process.
Unlike TIG welding, MIG welding
(a) requires no flux
(b) uses consumable electrodes
(c) provides complete protection from
atmospheric contamination
(d) requires no post-weld cleansing.
The major power supply used in MIG
welding is
(a) a.c. supply
(b) DCSP
(c) electrode-negative
(d) DCRP.
MIG welding process is becoming increa- singly
popular in welding industry mainly because
of
(a) its easy operation
(b) its high metal deposit rate
(c) its use in both ferrous and nonferrous
metals.
(d) both (a) and (b).
A weld bead of wineglass design is
produced in …………………. welding.
(a) plasma arc
(b) electron beam
(c) laser
(d) MAG.
Spot welding process basically depends on
(a) Ohmic resistance
(b) generation of heat
(c) application of forging pressure
(d) both (b) and (c).
Electric resistance seam welding uses
…………………… electrodes.
(a) pointed
(b) disc
(c) flat
(d) domed.
Projection welding can be regarded as a mass
production form of ………….. welding.
(a) seam
(b) butt
(c) spot
(d) upset.
In the process of electroslag welding,
theoretically there is no upper limit to the
(a) thickness of weld bead
(b) rate of metal deposit
(c) slag bath temperature
(d) rate of slag consumption.
High temperature metals like columbium
can be easily welded by………………… welding.
(a) flash
(b) MIG
(c) TIG
(d) electron beam.
During resistance welding heat produced at
the joint is proportional to
(a) I2R
(b) kVA
(c) current
(d) voltage
Grey iron in usually welded by ……. welding
(a) gas
(b) arc

The metal surfaces, for electrical resistance
welding must be…….
(a) lubricated
(b) cleaned
(c) moistened
(d) rough
In a welded joint poor fusion is due to which
of the following?
(a) Improper current
(b) High welding speed
(c) Uncleaned metal surface
(d) Lack of flux
For arc welding, D.C. is produced by which
of the following?
(a) motor-generator set
(b) regulator
(c) transformer
(d) none of the above
….. welding process uses consumable
electrodes.
(a) TIG
(b) MIG
(c) Laser
(d) All of the above
Which of the following equipment is generally
used for arc welding?
(a) single phase alternator
(b) two phase alternator
(c) three phase alternator
(d) transformer
Which of the following is not an inert gas?
(a) argon
(b) carbon dioxide
(c) helium
(d) all of the above
Electronic components are joined by which of
the following methods?
(a) brazing
(b) soldering
(c) seam welding
(d) spot welding
(e) none of the above
Resistance welding cannot be used for
(a) dielectrics
(b) ferrous materials
(c) non-ferrous metals
(d) any of the above
Electric arc welding process produces
temperature upto
(a) 1000oC
(b) 1500oC
(c) 3500oC
(d) 5550oC
Increased heat due to shorter arc is harmful on
account of
(a) under-cutting of base material
(b) burn through
(c) excessive porosity
(d) all of the above
Arc blow results in which of the following?
(a) Non-uniform weld beads
(b) Shallow weld puddle given rise to weak
weld
(c) Splashing out of metal from weld puddle
(d) All of the above defects
Inseam welding
(a) the work piece is fixed and disc electrodes
move
(b) the work piece moves but rotating
electrodes are fixed
(c) any of the above
(d) none of the above
In arc welding major personal hazards are
(a) flying sperks
(b) weld spatter
(c) harmful infrared and ultra-violet rays from
the arc
(d) all of the above
In spot welding composition and thickness of
the base metal decides
(a) the amount of squeeze pressure
(b) hold time
(c) the amount of weld current
(d) all above
Helium produces which of the following?
(a) deeper penetration
(b) faster welding speeds
(c) narrower heat affected zone in base metal
(d) all of the above
Due to which of the following reasons
aluminium is difficult to weld?
(a) it has an oxide coating
(b) it conducts away heat very rapidly
(c) both (a) and (b)
(d) none of the above
Welding leads have
(a) high flexibility
(b) high current handling capacity
(c) both (a) and (b)
(d) none of the above
Air craft body is
(a) spot welded

(b) gas welded
(c) seam welded
(d) riveted

For arc welding current range is usually
(a) 10 to 15 A
(b) 30 to 40 A
(c) 50 to 100 A
(d) 100 to 350 A
Spot welding is used for
(a) thin metal sheets
(b) rough and irregular surfaces
(c) costings only
(d) thick sections
Galvanising is a process of applying a layer of
(a) aluminium
(b) lead
(c) copper
(d) zinc
A seamless pipe has
(a) steam welded joint
(b) spot welded joint
(c) arc welded joint
(d) no joint
Motor-generator set for D.C. arc welding has
generator of
(a) series type
(b) shunt type
(c) differentially compound type
(d) level compound type
Plain and butt welds may be used on materials
upto thickness of nearly
(a) 5 mm
(b) 10 mm
(c) 25 mm
(d) 50 mm
In argon arc welding argon is used as a
(a) flux
(b) source of heat
(c) agent for heat transfer
(d) shield to protect the work from oxidation
During arc welding as the thickness of the
metal to be welded increases
(a) current should decrease, voltage should
increase
(b) current should increases, voltage remaining
the same
(c) current should increase, voltage should
decrease
(d) voltage should increase, current remaining
the same
In D.C. arc welding
(a) electrode is made positive and workpiece
negative
(b) electrode is made negative and workpiece
positive
(c) both electrode as well as workpiece are
made positive
(d) both electrode as well as workpiece are
made negative
The purpose of coating on arc welding
electrodes is to
(a) stabilise the arc
(b) provide a protecting atmosphere
(c) provide slag to protect the molten metal
(d) all of the above
50 percent duty cycle of a welding machine
means
(a) machine input is 50 percent of rated input
(b) machine efficiency is 50 percent
(c) machine work on 50 percent output
(d) machine works for 5 minutes in a duration
of 10 minutes

(b) 2. (d) 3. (a) 4. (c) 5. (c) 6. (a 7. (c) 8. (b) 9. (d) 10.(a) 11. (c) 12. (b) 13. (d) 14. (d) 15. (a) 16. (d) 17. (b) 18. (c) 19.(a) 20. (d) 21. (a) 22. (a) 23. (b) 24. (a) 25. (a) 26. (b) 27. (d) 28.(b) 29. (b) 30. (a) 31. (d) 32. (d) 33. (d) 34. (c) 35. (d) 36. (d) 37.(d) 38. (c) 39. (d) 40. (c) 41. (d) 42. (a) 43. (d) 44. (d) 45. (d) 46.(c) 47. (d) 48. (b) 49. (b) 50. (d) 51. (d)

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