| 摘要 |
The present invention relates to a magnet (100), which comprises a body (102) and a first slide (101) arranged to be movable relative to the body (102) between a first and a second position. The first slide (101) comprises a first permanent magnet (106), and a first and a second pole piece (107, 108) attached to opposite magnetic pole sur- faces of the first permanent magnet (106). The body (102) comprises a first and a second plate (103, 104), which are arranged in parallel and at a first distance from each other. The second plate (104) comprises a first through hole (109), in which the first slide (101) is movably arranged so that the first pole piece (107) is directed towards the first plate (103), wherein at the first position of the first slide (101), the first pole piece (107) is located outside the first through hole (109) and at least part of the second pole piece (108) is located inside the first through hole (109), and at the second position of the first slide (101), the first permanent magnet (106) and at least part of the first and the second pole piece (107, 108) are located inside the first through hole (109). |
