Two metal strips, each of length `l` and thickness `d` at temperature `T_(0)` are riveted together so that their ends coincide. One strip is made of metal `A` having a linear coefficient `alpha_(B)` where `alpha_(A)gtalpha_(B)` . When this bimetallic-strip is heated to a temperature `(T_(0)+DeltaT)` , one strip becomes longer than the other and the bimetallic strip bends into an arc of a circle. What is the radius of curvature `R` of the strip ?