在物理学中,指能发出一定波长范围的电磁波(包括可见光与紫外线、红外线、X射线等不可见光)的物体。通常情况下指能发出可见光的发光体。凡物体本身能发光者,称做光源,又称发光体。如太阳、恒星、灯以及燃烧着的物质等都是光源。
2022-10-22 14:02:34
2024-04-19 20:43:13
2024-03-22 19:08:17
2022-10-29 17:07:46
2024-03-08 16:39:24
2024-04-18 02:00:24
2024-03-10 21:24:03
2024-04-10 05:47:41
2024-04-11 08:50:19
2024-04-02 22:48:33
2024-03-19 06:01:48
2023-02-13 15:04:32
2020-10-28 09:44:53
2023-03-06 09:17:20
2023-02-03 09:09:58
2023-04-22 17:20:06
2024-04-10 19:34:02
2020-10-28 13:35:07
2023-04-24 16:04:10
2024-04-21 09:42:55
2024-04-05 10:33:50
2023-03-08 09:33:01
2024-04-23 04:22:13
2024-04-05 13:44:05
2024-03-13 08:36:52
2023-01-10 14:22:54
2022-06-13 17:29:08
2024-04-22 22:35:15
2024-04-11 20:04:31
2023-01-06 09:30:15
2024-04-20 12:54:06
2024-04-10 10:33:57
2022-10-13 16:40:47
2024-03-12 02:08:30
2024-03-29 03:27:21
2024-04-03 14:14:38
2023-02-15 15:58:42
2024-04-14 17:00:35
2024-04-13 04:27:47
2024-03-14 10:02:33
2024-04-12 18:17:30
2024-04-13 13:24:43
2023-03-02 15:17:27
2023-04-07 15:12:16
2024-03-25 20:58:05
2021-06-25 08:56:44
2024-03-12 13:19:02
2024-03-11 18:25:00
2024-03-20 17:26:24
2023-04-19 11:36:28