To trace hystersis curves on CRO using resistance, capacitance & inductance, instrument comprises of AC power supply 3-15V, output selectable using band switch, printed circuit diagram, components connected behind the front panel, provision for connecting external inductance is given, input & output connections brought out at sockets.BH Curve Apparatus is an essential laboratory instrument used in the field of electromagnetism and material science to study the magnetic properties of materials. It is specifically designed to graphically depict the relationship between magnetic field strength (H) and magnetic flux density (B) for a given material, known as the BH curve The apparatus includes a sample of the magnetic material under investigation. This material can vary and may include ferromagnetic, paramagnetic, or diamagnetic substances. The sample's characteristics directly influence the shape of the BH curve.