This document describes how to study the B-H curve of materials using an oscilloscope (CRO). It discusses the apparatus needed including a B-H curve cabinet, transformer, sample coil, CRO and other components. The aim is to trace and study the B-H loop of ferromagnetic materials. The document provides background on magnetism, different types of magnetic materials like diamagnetic, paramagnetic and ferromagnetic, and concepts like domains, Curie temperature and hysteresis. It outlines the procedure to connect the components and record the hysteresis loop on tracing paper to analyze properties like retentivity and coercivity. Potential applications are also mentioned like in magnetic tapes, hard disks and credit cards.