ABSTRACT
A change in temperature will change the size of a diaphragm and its modulus of elasticity as well. When a solid material is at any temperature above absolute zero, the atoms have thermal energy and vibrate about their equilibrium positions. The higher the temperature, the larger the amplitude of Vibration. The mean position of the atoms change with increasing temperature, the atoms tending to move apart as the temperature is raised. This phenomenon, which occurs within the atomic structure of the material, is known as thermal expansion and is usually calculated by the coefficient of thermal expansion. The coefficient of thermal expansion is a measure of the length increase of a macroscopic sample for a given temperature increase. The elastic modulus decreases with increase in temperature. This chapter provides the average values of the thermal coefficients of expansion and modulus of elasticity of various instrument materials.
