Secondary contamination
Gravity Electro-magnetic force Direct impact or contact
A system is said to be closed when it doesn't interact with the outside world. This is a theoretical idea; in real systems, it is impossible to entirely eliminate contact with other parts of the Universe.
If you mean that the light is in the glass, and the air is on the "outside", then yes. The other way it isn't possible; for total internal reflection, the material through which light travels must needs have a higher refractive index.
The image you see the the reflection of light from the object into your eyes. During the day time, light from the object incident and reflect to your eyes as well as light from the outside refract to your eyes. Therefore, you barely notice the image. At night, however, there is no source of light from the window outside. As a result, there is only light from the object(yourself) reflect back to your eyes. Hence, your image is visible on the window at night.
This is to stop condensation from forming on the top of the lid. Condensation causes two problems (1) It will allow contamination to enter into the dish by moving accross the water film from the outside (2) It can create a tight seal and prevent oxygen entering the petri dish making it go anerobic.
Secondary contamination
Secondary contamination
Secondary contamination
Secondary contamination
Secondary contamination
Exposure
Exposure
Hot Hazard Zone
Hot Hazard Zone
incident command post
Sometimes the workers at nuclear power plants do get contaminated. In general the contamination is mild, and most workers never experience such a thing. A few have been seriously injured by radiation, but, aside from the Chernobyl and Kyshtym disasters and the Windscale Fire, this has very rarely happened. Aside from the three accidents mentioned above and contamination from nuclear bombs, the worst radiation contamination problems have been outside the nuclear industry. The so called Radium Girls are one example, in which contamination killed a number of workers at different industrial facilities in the United States during the 1920s. The worst recent contamination problem was the Goiania accident, in Brazil in 1987, in which radioactive cesium was distributed from abandoned medical equipment.
Plants do absorb some radiation from contamination by airborne radiation or from the soil after contaminated dust has settled on it. Marijuana would be similar if grown outside, however I believe some is grown in indoor warm rooms, this should be clear. Not a good idea to smoke something that is contaminated though, probably more harmful than eating some food with similar contamination, as that would pass through you fairly quickly whilst if absorbed into the lungs it could stay there some time (I am not medically qualified, just giving my thoughts)