| 摘要 |
The device comprises a transparent tube (1) wherein may slide freely a part (4) at the extremities of which are arranged two small magnetic masses (5, 6). The tube (1), closed at both ends, forms a sealed tank wherein there is placed a phase changing material (7) which is either in a liquid state or in a solid state, according to the temperature to which it has been brought. At one of the ends of the tube (1) a cap (12) containing a removable magnet (9a) is fitted. A fixed magnet (11) is placed at the other end of the tube (1). The part (4) being initially placed on the side of the cap (12), the material (7) is solidified and the removable magnet (9a) is then removed. In the case of exceeding the melting temperature of the material (7), the part (4) attracted by the magnet (11) moves towards the corresponding end of the tube (1), thus making visible a coloured ring (14). |
