For spot welding of 1 mm thick sheet with a current flow time of 0.2 s, the heat generated is 1000 J. If the effective resistance is 200 μΩ, the current required is

Question

Question

This question was previously asked in

ESE Mechanical 2018 Official Paper

Answer 1

Concept:

Heat generated (Q) in the spot welding is given by, Q = I²× R × t

Where I is the flow of current, R is the resistance and the t is the duration for which the current flows

Calculation:

Given, Current flow time t = 0.2 s, Heat generated = 1000 J and, Resistance = 200 μΩ

1000 = I²× 200 × 10^-6 × 0.2

I = 5000 A