1. Diamagnetism is a property exhibited by certain materials that causes them to create a weak magnetic field in opposition to an externally applied magnetic field.

反磁性是某些材料表现出的一种性质，使它们在外加磁场下产生与之相反的弱磁场。

2. Diamagnetism can be observed in various substances such as water, copper, and bismuth.

反磁性可以在各种物质上观察到，如水、铜和铋。