Before revision: The curvature of a bimetallic beam can be described by the following equation : where and is the radius of curvature, and are the Young's modulus and height (thickness ) of material one and and are the where is the total thickness of the bimetal and is a dimensionless coefficient.
After revision: The curvature of a bimetallic strip depends on temperature according the formula derived by French physicist Yvon Villarceau in 1863 in his research for improving the precision of clocks : ,radius of where is the total thickness of the bimetal and is a dimensionless coefficient.