This demonstration device is a portable and visual teaching equipment that can visually present the complete working principle of transformers in the classroom or laboratory within 2 minutes, helping students understand core concepts such as electromagnetic induction, turns ratio, energy conversion, and efficiency. Typical experiment: Verify the relationship between turns ratio and voltage conversion; Measurement of no-load current and iron loss; Short circuit impedance and copper loss measurement; Draw efficiency curves under different loads; Observe the phenomenon of magnetic saturation (with detachable air gap gasket attached). Applied to physics and electrical engineering teaching in middle schools and universities, as well as electrical training in vocational colleges.