Which of the following is closest to an ideal black body?
1. | Black lamp |
2. | Cavity maintained at a constant temperature |
3. | Platinum black |
4. | A lump of charcoal heated to high temperature |
We consider the radiation emitted by the human body. Which of the following statements is true:
1. | The radiation emitted is in the infrared region |
2. | The radiation is emitted only during the day |
3. | The radiation is emitted during the summers and absorbed during the winters |
4. | The radiation emitted lies in the ultraviolet region and hence is not visible |