This is an effective apparatus to determine the Rigidity Modulus of a test rod by subjecting it to torsional (twisting) force. This experiment helps to develop a fundamental understanding of the concept as all forces in play can be easily visualized. Comprising of cast iron v shaped supports joined by two supports rods one of which graduated in cm or mm, one sided support is  fitted with  wheel of 165mm diameter moves on ball bearings is provided self centering chuck to hold one end of the test rod of 55cm long and the  other end of the rod clamped tightly in V shaped support, two pointers and two scales graduated 30-0-30 in single degrees slides or clamped along the support rod ,two test rod of brass & steel is provided. Supplied without weights.