方形线圈用于演示和说明：1、磁场对电流作用时，磁场方向、电流方向和磁场对电流作用方向之间的关系——左手定则；2、在电磁感应现象中，磁场方向，导线运动方向和感生电流方向之间的关系——右手定则。
J2419  A Square Coil
It is used for the demonstration and explanation: 1, on the current role of the magnetic field, magnetic field direction of the current direction of the magnetic field and current role in the direction of the relationship between - left-handed rule; 2, the phenomenon of electromagnetic induction, the magnetic field direction of the wire movement Induced current direction and the direction of the relationship between - right-hand rule.