This experiment aims to determine the modulus of rigidity of a mild steel or cast iron specimen through a torsion test. The torsion test will be conducted using a torsion testing machine and angle of twist measuring attachment. Observations of the maximum twisting torque and angle of twist will be recorded. These values along with the specimen's length and polar moment of inertia will be used in the torsion equation to calculate the modulus of rigidity. Precautions such as ensuring the specimen remains within its elastic limit will be followed to obtain accurate results.