Two castings of the same metal have the same surface area one casting is in the form of a sphere and the other is a cube. What is the ratio of the solidification time for the sphere to that of cube.

A strip with sectional area $$150mm\,\, \times \,\,4.5mm$$ is being rolled with $$20\% $$ reduction of area using $$450mm$$ diameter rollers. The angle subtended by the deformation zone at the roll center is (in radians)

The voltage-arc length characteristics of a $$DC$$ arc is given by $$V=20+4L.$$ Where $$L$$ is in $$mm$$. During a welding operation arc length is expected to vary between $$4$$ and $$6$$ $$mm$$ with the welding current limited between $$450$$ and $$550$$amps.

The arc power at an arc length of $$5mm$$ is

The voltage-arc length characteristics of a $$DC$$ arc is given by $$V=20+4L.$$ Where $$L$$ is in $$mm$$. During a welding operation arc length is expected to vary between $$4$$ and $$6$$ $$mm$$ with the welding current limited between $$450$$ and $$550$$amps.

If the power source has a linear characteristic, the open circuit voltage is.