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GATE 2020 PI – Question 55

Manufacturing Processes I · Joining of Materials · 2 marks · Numerical answer

A resistance spot weld initially generates2000 J. With resistance unchanged, current rises25% and duration halves. Find new heat in J (one decimal).

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Correct answer: 1560.0 to 1563.0

Explanation

Joule heat is I²Rt. Thus Q₂/Q₁=(1.25)²(0.5)=0.78125. New heat is2000×0.78125=1562.5 J. Current affects heat quadratically, while duration affects it linearly.

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