Define the terms stress and strain and also state their SI units. Draw the stress versus strain graph for a metallic wire, when stretched upto the breaking point.

What does the slops of stress versus strain graph indicate?

Define stress and strain and derive their units. What is Hooke's law? Write its one limitation.

Define the terms resistivity and conductivity and state their S. I. units. Draw a graph showing the variation of resistivity with temperature for a typical semiconductor.

Define the term electrical conductivity of a metallic wire. Write its SI unit.

The stress strain graph for a metal wire is shown in the fig. Upto the point E, the wire returns to its original state O along the curve EPO, when it is gradually unloaded. Point B corresponds to the fracture of the wire. (a) Upto what point on the curve is Hooke's law obeyed? (this point some times called proportional limits). (b) Which point on the curve corresponding to elastic limet or yield point of the wire? (c ) Indicate teh elastice and plastic regions of the stree-strain graph. (d) Describe what happens when the wire is loaded upto a stress corresponding to the point A on the graph and then unloaded gradulally. In particular explain the dotted curve. (e) Wht is peculiar about the protion of the stree- strain graph from C to B? Upto what stress can the wire be subjected with out causing fracture?

The point on stress-strain graph at which the plastic flow starts is known as

Figure shows graph between stress and strain for a uniform wire at wo different temperatures. Then

A graph is shown between stress and strain for a metal. The part in which Hooke's law holds good is