When we put a closed bottle filled with cold water in the room small droplets of water appeared on it. this is due to ___.

Key concepts Physics Liquids Gasses Pressure Introduction Ever wonder where those little drops of water on the outside of your cold can of soda pop or bottle of water come from? That’s condensation! Cold surfaces can cause water vapor in the air to cool down, condense and form tiny beads of liquid. The molecules in these miniscule droplets of water are grouped far more closely together than when they were in their gas phase, and exert less pressure—a fact that has some pretty cool physical implications. Perhaps you have seen the classic science demonstration where a hard-boiled egg is “sucked” into a bottle using a match. The effect is definitely cool, but understanding how it works is tough. Air molecules are spaced differently and exert different levels of pressure depending on how hot or cold they are. This is a fun experiment where the physics are more observable, the effect more dramatic and the pyrotechnics totally unnecessary. Background Molecules, which make up everything around us—including air—are in a constant state of motion. The hotter water molecules become, the faster they move, turning from water (their liquid phase) to steam (their gas phase). When liquid water turns to gas, not only do the molecules move much faster, they also are spaced much farther apart. They spread out so much that they generate pressure by pushing on each other and everything else they come into contact with. What happens when we take the heat source away from that steam? The molecul...

So, I noticed that in a closed plastic bottle (say only less than half full) little droplets of water were condensed on one side of the internal surface. That was the side exposed to sun rays. Why should water condense were sun rays hit more directly? I would expect that water would condense on the (sensibly) colder portion of the internal surface. I can see that water vapor inside the bottle maybe absorbs more energy from the sunrays and therefore tends to condense on the (colder) plastic surface. But why on the side where sun hits more directly? I think I observed the same with a 70 W lightbulb. My theory is also about the focusing of the light, but is opposite your idea in many ways: The bottle and water both transmit light fairly well, so I see no reason to presume that the side nearer the sun is the warmer side. I am guessing that the focus of the reflected light off the far side of the bottle is the most important thing here. That area will be about R/2 away from the side of the bottle AWAY from the sun, and I hypothesize that that is the warmest area and therefore the rising warm air side of a convection cell in the gas above the water. That leaves the cooler condensing gas to flow back down the side of the bottle nearer the sun. $\begingroup$ Mmmm I did not think of reflection.. Anyways I'm thinking that maybe the bottle-induced focusing is more or less symmetric and what makes the real difference is that as soon as a small portion of water vapor condenses evenly a...

When the water is warmer, it has a higher vapour pressure making tiny droplets of water (water vapour) more likely form in the air inside the bottle. These droplets will then condense when they make contact with the side of the bottle because it is cooler there. -Alex listin that's soo boring i mean tlk about somtin eles How could you use a bottle taken from the fridge to show there is water vapor in the air? Leave it on the side to warm up, and condensation will form on the inside- little water droplets. As you haven't messed with the bottle at all (ie added anything to it) it should bepure air and therefore shows there is water vapour in the air.

What causes condensation? According to National Geographic, condensation is the opposite of evaporation and is the process where water vapor in the air becomes a liquid. It can happen in one of two ways. For condensation to form, water vapor is either cooled to its dew point– which is the temperature at which water in the air condenses to create water droplets. Or, the air becomes so saturated with water vapor that it can't hold any more water. These include: • The humidity of indoor air– As we touched on before, condensation forms when the inside air can’t hold the level of moisture • Low temperature– The humid air comes into contact with cold indoor surfaces • Poor ventilation– If there is nowhere for the hot and cold air to go, the humidity accumulates indoors and leads to increased condensation This is why, as Tim Carroll, from the (Image credit: Getty) The difference between condensation inside and outside your windows When you see water droplets outside your windows, this is called dew. As stated by National Geographic, dew is the moisture that forms as the result of condensation, therefore it is the end result of water vapor changing to liquid form. Dew only occurs when temperatures drop and objects cool down. Unlike hot air, colder air is less able to hold water vapor, which forces the gaseous water around cool objects to condense. Temperatures reach the dew point most usually at night –and especially during summer when warm days are followed by cool nights. This i...

Key Concepts Physics Air pressure Water pressure Surface tension Introduction Did you know that at sea level there are about 15 pounds of air pressing on each square inch of your body? This air is very helpful in our daily lives. For example, the layer of air around the earth helps to keep it from getting too cold or hot. It can even help keep a bottle with holes in it leak-free! Try the activity to find out how. Background Earth is covered by the atmosphere, which is a blanket of gas that is 60 miles thick [two things: we should stick to metric or non-metric and since the "15 pounds of pressure" is a sort of standard we should stick with non-metric; also, there are so many figures for thickness because there's no set boundary—I'm taking "60" from here: https://www.grc.nasa.gov/www/k-12/airplane/atmosphere.html]. Although we usually think of air as not being full of anything, all air is made up of tiny particles, which have a small amount of mass. We—and anything else around us—experience the weight of this layer of gas as pressure; this is called atmospheric pressure. We are so used to this pressure, however, that we rarely notice its existence. But if you have ever felt your ears "pop" while driving up a mountain, you noticed it changing. As you drive up in elevation, fewer layers of air press on you. The air inside your eardrums remained at the air pressure from a lower elevation—at least, until they "popped." Water is also made up of tiny particles that have mass. When...

The first step is to realize that warm water will evaporate more rapidly than cool water. You probably know that already. If a cup of iced tea were set next to a cup of hot tea you probably be able to tell which was which by just looking at them. You wouldn't need to touch the cups or taste the tea or look for ice cubes. You would probably notice that one of the cups of tea was steaming (the cup on the right above). That would be the hot tea. The steam that you see is not actually water vapor. Rather water vapor is evaporating so quickly that it is filling the cooler air above with more moisture than it can handle (the relative humidity is over 100%, the air is super saturated with moisture). The excess water vapor condenses (bringing the relative humidity down to 100%) and forms a faint cloud of very small drops of water. That's what you are seeing. Here are the two cups again with arrows drawn in to represent the different rates of evaporation. One arrow is shown evaporating from the cup of cold water. We'll just assume the warmer water at right is evaporating 3 times more rapidly. The actual numbers aren't important, the important point is that the warm water evaporates more quickly than the cold water. Next we'll pour out the tea and fill a cup with some room temperature water and let it sit on a table for a day or two. The water will still evaporate; that depends on the water's temperature, it doesn't matter whether the cup is covered or not. The cover keeps the water...