The device is similar to Newton’s Rings apparatus except that an arrangement for loading the test piece is provided for carrying out Cornus interference studies. The objective of this experiment is to determine Poisson’s ratio and Young’s modulus for different materials (glass and perspex) using interference method. Sodium vapor lamp is used as light source. The readings from the interference pattern is observed through a micrometer driven traveling microscope which is made integrated with the device.
The objective of this experiment is to determine Poisson’s ratio and Young’s Modulus for different materials (glass, perspex etc.) using interference method. Weights are positioned at both ends of the bar, causing it to bend longitudinally downward and hence laterally upward. A glass plate is placed on the bar to produce an interference pattern. By examining the interference pattern, extent of longitudinal and lateral bending can be determined and Poisson ratio and Young’s modulus of the bar can be deduced.
If the longitudinal strain of the perspex beam produces a radius of curvature R1 and the lateral strain produces a radius of curvature R2 then Poisson ratio can be calculated from R1 & R2
