WELDING MCQ SET 5
Q1. The time during which current flows in resistance welding is called:
A) Heating time
B) Welding time
C) Squeeze time
D) Hold time
Answer: B) Welding time
Explanation: It is the duration of current flow that produces heat for joining.
Q2. In gas welding, backfire occurs when:
A) The flame goes out suddenly
B) The flame enters the torch
C) Gas pressure is equal
D) Cylinder is full
Answer: B) The flame enters the torch
Explanation: Backfire happens due to improper gas pressure or faulty torch operation.
Q3. The safety device used between gas cylinder and regulator is:
A) Flashback arrestor
B) Pressure gauge
C) Nozzle
D) Filter
Answer: A) Flashback arrestor
Explanation: It prevents flame from flowing back into the gas cylinder, ensuring safety.
Q4. The color of oxygen cylinder is:
A) Blue
B) Black with white top
C) Red
D) Yellow
Answer: B) Black with white top
Explanation: Standard color coding identifies gas type โ oxygen is black with a white top.
Q5. The color of acetylene cylinder is:
A) Red
B) Yellow
C) Blue
D) Green
ย Answer: A) Red
Explanation: Acetylene cylinders are colored red for easy identification and safety.
Q6. In MIG welding, the electrode is:
A) Non-consumable
B) Consumable wire
C) Tungsten rod
D) Copper plate
Answer: B) Consumable wire
Explanation: The wire electrode melts and acts as both filler and electrode in MIG welding.
Q7. The main advantage of MIG welding is:
A) Slow speed
B) No filler required
C) High deposition rate and clean weld
D) Low efficiency
Answer: C) High deposition rate and clean weld
Explanation: MIG welding gives smooth welds, faster operation, and minimal cleaning.
Q8. TIG welding is most suitable for:
A) Thick mild steel
B) Stainless steel and aluminum
C) Cast iron
D) Brass
Answer: B) Stainless steel and aluminum
Explanation: TIG gives high-quality welds on non-ferrous metals and thin sections.
Q9. The current used in TIG welding of aluminum is:
A) DCEN
B) DCEP
C) AC
D) DC only
Answer: C) AC
Explanation: AC current helps in removing oxide film from aluminum during welding.
Q10. The main cause of undercut in welding is:
A) Excessive current or high speed
B) Low current
C) Low heat
D) Short arc length
Answer: A) Excessive current or high speed
Explanation: Too much heat or fast travel speed erodes base metal edges, creating an undercut defect.
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