Torsion Apparatus – Searle’s Vertical Type, also known as Barton’s Apparatus, is a precision instrument used for determining the modulus of rigidity of a rod by applying torsional force. It is designed for advanced mechanics and elasticity experiments in physics laboratories.

The apparatus is constructed with a strong steel frame mounted on a heavy cast iron base, supported by a vertical rod and fitted with levelling screws for stable alignment. A test rod of approximately 900 mm length and 5 mm diameter is firmly held between a three-jaw chuck and a torsional drum. The drum is rotated using a string arrangement passing over two frictionless pulleys and connected to a scale pan.

For accurate measurement of angular deflection, the apparatus includes three adjustable circular scales graduated in single degrees, along with corresponding pointers. It is supplied with three additional test rods, strings, and two scale pans. Supplied without weights.


Experimental Objectives

To determine the modulus of rigidity of a given rod using Searle’s vertical torsion method.
To study the effect of applied torsional force on angular deflection.
To understand the relationship between torque, angle of twist, and rigidity modulus.
To demonstrate elastic behavior of rods under torsional stress.