Torsion pendulum consists of c.p solid brass circular disc of diameter  125 mm and 0.50 mm thick  , one end of suspension wire hangs from a Universal Clamp and the other end is clamped to a pin-vice nut of disc fitted on one side, moreover heavy metal ring of brass of same dia 5” is attached to the disc. When ring is placed on the disc, the moment of inertia, and therefore the period of vibration of the system, is Increased. Precise and simple, the Vashishat Torsion pendulum is designed to study the torsional elasticity of a metal wire. Using pendulum's movement, the measurement of the balance oscillating period allows us to determine the modulus of rigidity  (?)  of  the  material  of  a   given  wire  using torsion pendulum.