Welding of $$C40$$ steel plate of $$10mm$$ thickness required a current of $$16$$amps, while it was $$360$$amps when the plate thickness was increased by $$50\% $$. Estimate the welding current for $$8mm$$ thickness of same material.

The cross section weld bead is shown in fig the profile of the bead and the fusion zone are taken circular for convenience. Bead width and radii of curvature of circular profiles are given in fig. The bead height and depth of penetration are

A low carbon steel is to be welded by the manual metal arc welding process using a linear $$V$$-$$I$$ characteristic $$DC$$ power source.

The following data is available.
$$O.C$$ voltage of the power source $$=62V,$$
$$S.C$$ current for the setting used $$=130A,$$
ARC length $$=4mm,$$
Traverse speed of welding $$=15cm/min$$
Efficiency of heat input $$ = 85\% $$
The relation between the arc length $$L$$ in $$mm$$
and arc voltage $$V$$ is $$V=20+1.5L$$
Calculate the heat input into the work piece.

Manual metal arc welding is to be used for welding two plates each measuring $$800 \times 200 \times 19mm.$$ Given that
Length of weld $$\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,\,$$$$:180mm$$
Length of electrode$$\,\,\,\,\,\,\,\,\,\,\,$$ $$:450mm$$
Stub length$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,\,$$ $$:50mm$$
Diameter of electrode $$\,\,\,\,\,$$ $$:3mm$$
Weld reinforcement area $$:10\% $$
Spatter and other losses $$:15\% $$
Root gap $$=$$ land $$=$$ $$2mm$$
Angle of groove$$\,\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,$$ $$:{60^ \circ }$$
Estimate the required number of electrodes for the weld.