Can ultraviolet rays kill cockroaches? Cockroaches are rampant at home and don't want to use poison. Who has used ultraviolet light? Tell me about the effect.

Ultraviolet rays can kill bacteria, but they can't kill cockroaches. Ultraviolet rays are mainly used for air disinfection and surface disinfection in sterile rooms and some working areas.

What effect does the fluctuation of moving charge have on the small magnetic needle? Take linear current as an example for analysis. The small magnetic needle n is located on the right side of the linear current I. When the small magnetic needle n is simplified as the annular current abcd, although the points A, B, C and D are all within the fluctuation range of the linear current I, the energy of the adjacent movements of the points A, B, C and D is different.

Obviously, Ea & gtEc, Eb=Ed. In this way, the fluctuation of the line current I has a clockwise moment on the annular current abcd of the small magnetic needle N, which acts on the electrons rotating around the nucleus to make them rotate clockwise, and its macro performance is that the north pole of the small magnetic needle N faces outwards.

Related extensions:

The moving charge will fluctuate. The fluctuation mechanism is that when the moving charge E moves, it is bound to be hindered by its neighbor E, which shows that the moving charge drives its neighbor 1 to move upward, that is, the neighbor moves upward with the moving charge E.

When the adjacent 1 moves upward, it is bound to be hindered by its own adjacent 1, which means that the adjacent 1 drives its own adjacent upward movement, that is, the adjacent 2 moves upward together with the adjacent 1. This spread forward, forming fluctuations. Obviously, the propagation speed of this wave in a vacuum is the speed of light.