Two identical rectangular plates of copper and steel are riveted together to form a bimetallic strip. If it is heated then it will (i) remain straight, (ii) bend with the copper plate at the convex side, (iii) bend with the steel plate at the convex side, (iv) get twisted. Choose the correct alternative with justification. Given: for copper $\alpha =17\times {10}^{-6}/°C=$ and for steel $\alpha =12\times {10}^{-6}/°C$.