Take a metallic ball and ring. The diameters of the ring and the ball are such that ball is just able to pass through the ring at the room temperature. Now heat the ball and try to pass the ball through the ring. It does not pass through the ring. This clearly shows that on heating the diameter of the ball has increased i.e., the solid has expanded. Now cool the ball to room temperature. After cooling it is found that ball passes through the ring which clearly shows that diameter of the ball has decreased, i.e., the solid contracts on cooling.
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