Category: Convection smoke box experiment

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Convection smoke box experiment

Post a Comment. Smoke chimney experiment. Download the above picture. When you open the picture you will find a picture of a rectangle with two openings. Inside you can see a candle with a flame. At the opening of the chimney on the right side, you can see an incense stick. That is why this experiment is called the smoke chimney experiment. When the incense stick is lit up, smoke enters the box from the right-hand chimney.

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Your job is to draw arrows representing the path that you think the smoke will follow. You can do this by copying the downloaded picture in a Paint program installed on your computer and drawing arrows where you think is correct. When you are ready, save the picture and upload it here on the blog and share your ideas on how you arrived at this conclusion. Here are some questions that can help you conclude the arrow direction of the smoke:. How is the air inside the box warmed?

What will happen to the smoke when it enters the box? Why did this occur? What happens to the air just above the lit candle? I will be demonstrating this experiment in class in the following days. In the meantime post your predictions and we will deal with them in class. Good luck!

No comments:. Newer Post Older Post Home. Subscribe to: Post Comments Atom.Water Cycle - Atmosphere 1 Post Lab. Wind is caused by cool air that moves in to replace rising warmer air. Warmer air rises because the same number of molecules takes up more space.

Because it is less dense, the warm air floats on colder air. A convection oven uses the principle of moving heated air throughout the oven, which cooks evenly from the top and bottom. A conventional stove cooks from the bottom up. Demonstrate the following to emphasize moisture, wind, heat, and air. Show condensation by putting a plastic bag over a plant a day before you show students. Moisture will accumulate on the plastic bag.

Note that this is one reason why forests feel wetter than deserts. Breathe on a mirror to show that you can get moisture from air. Place the chimneys cardboard tubes from toilet paper rolls over the holes.

Heat Convection in Liquids

Stick pins into incense cones so that you can hang the cone in the top of the chimney opposite the candle. Light the candle. Wait a minute or so, then light the incense. Hot air rises over the candle and pulls in cool air.

The smoke from the incense will travel through the box because the incense is at the cool air inlet. As the incense burns down, it may get hot enough for smoke to rise from it.


If this happens, replace it with a new cone. Explain that this box shows how wind is formed.

convection smoke box experiment

The candle is a hot area on the earth, and cool surrounding air is being pulled in. The smoke form the incense will travel through the box because the incense is at the cool air inlet. This box shows how wind is formed. The result will be more dramatic if the flask is cooled first. Place the flask in the hot water. The balloon will blow up. Ask the students why the balloon blew up.The science of weather affects all of us every day!

Convection, high-pressure and low-pressure systems, evaporation—these things help determine if our game will be rained out or if we will have a sunny day for sledding. Learn more about the way weather works by doing these hands-on experiments. Have you ever heard that hot air rises? As air heats up, its molecules expand and spread out, making the air less dense than it was before.

It floats up through the denser cooler air. As the warm air rises it starts to cool off and its molecules move closer together, causing it to sink again.

This circulation is called convection, and the rising and falling of the air are called currents. Convection currents are part of what causes different kinds of weather.

Do this experiment to find out! What happened? The hot water was less dense than the cold water surrounding it, so it rose to the top in a convection current. What happens as the colored water gets to the top? Does it stay there?

Why or why not? Air seems like the lightest thing in the world, but it actually pushes down on you and the ground with a great deal of force. This force is called air pressure. In the last experiment we saw that when air heats up it begins to rise. An area full of light, warm air is called a low-pressure zone.

Areas with cool, denser air are called high-pressure zones. What happens when a low-pressure zone and a high-pressure zone are right next to each other? Have an adult help you with the oven and matches. When you lit the candle the first time you did it in an area where the air pressure was constant, so the smoke flowed straight up.

When you set the pans side by side, the ice cooled the air around it, creating a mini high-pressure zone, and the sand warmed the air around it to create a mini low-pressure zone. Air always flows from a high-pressure zone to a low-pressure zone to even up the pressure — this is what causes wind. You made a tiny breeze between the pan of ice and the pan of sand, and the smoke floated sideways in the breeze.

The same thing happens between cold ocean water and hot beach sand, which is why there is almost always a breeze at the beach!

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Air pressure changes cause wind, but they are responsible for other types of weather too. A low-pressure zone usually causes clouds and rain, because as the hot air rises it carries with it evaporated moisture that can condense into clouds. A high-pressure zone usually results in clear skies and sunny days because sinking currents prevent moisture from rising up and forming clouds.

Try tracking the air pressure for a few days in your area and see how it relates to the weather. You can use a barometeror check the National Weather Service website.

Low-pressure zones create clouds because the rising hot air carries moisture with it. The moisture is in the form of a gas called water vapor. When the water vapor cools, it forms water droplets that join together to form clouds. How does the water vapor get into the air in the first place?Heat can be transferred from one place to another by convection.

Liquids and gases are fluids because they can be made to flow. The particles in these fluids can move from place to place. Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. Heat energy is transferred from hot places to cooler places by convection. Liquids and gases expand when they are heated.

This is because the particles in liquids and gases move faster when they are heated than they do when they are cold. As a result, the particles take up more volume. This is because the gap between particles widens, while the particles themselves stay the same size. The liquid or gas in hot areas is less dense than the liquid or gas in cold areas, so it rises into the cold areas.

The denser cold liquid or gas falls into the warm areas. In this way, convection currents that transfer heat from place to place are set up. Convection currents can be seen in lava lamps. The wax inside the lamp warms up, becomes less dense than the liquid and so rises. When it rises, it cools and becomes denser again, so it sinks. This same effect can be seen by putting a crystal of potassium permanganate in a beaker of water and gently heating it.

Convection explains why hot air balloons rise, and also why it is often hotter in the lofts of houses than downstairs. As well as these examples, convection is seen on a much bigger scale in our weather and ocean currents. Convection Heat can be transferred from one place to another by convection. Fluids Liquids and gases are fluids because they can be made to flow. Air current close to a radiator Heat energy is transferred from hot places to cooler places by convection. A beaker is heated and the coloured fluid inside shows convection currents.Unlike conduction, where heat is passed on from one section of the substance to another as described in the previous post transmission of heat energy explainedthe heat is here actually carried from one place to another in the liquid by the movement of the liquid itself.

This phenomenon is called convection. The same process occurs when a gas is heated. A finger is placed over the end of the tube, which is then removed, together with the colored water it contains.

This method of introducing the crystal ensures getting it in the centre and also prevents it from coloring the water before it is required. On heating the bottom of the flask with a very small gas flame an upward current of colored water will ascend from the place where heat is applied. This colored stream reaches the top and spreads out. After a short time it circulates down the sides of the flask, showing that a convection current has been set up.

Thus a warm convection current moves upwards; for the same reason a cork rises in water or a hydrogen-filled balloon rises in air. In effect, convection is an application of Archimedes' principle. For further illustration please read Balloons and floating bodies. If, on the other hand, some liquid in a vessel is heated at the top, the liquid there expands and remains floating on the denser liquid beneath. No convection current is set up, and the only way in which heat can travel downwards under these conditions is by conduction.

A suitable windmill may be cut with scissors from thin card or aluminium foil to the pattern on the image above. The vanes are slightly bent and the mill, pivoted on a piece of bent wire, is held over the top of an electric lamp.

convection smoke box experiment

When the lamp is switched on the windmill rotates in the upward hot air current. A device similar to this is often used to produce a glimmering effect in domestic electric heaters of a type which are disguised to resemble glowing coal fires. During the eighteenth century coal-mines were ventilated by sinking two shafts to the workings, known as the upcast and downcast shafts respectively.

A fire was lit at the bottom of the upcast shaft, which caused the air in it to become heated and rise.

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Fresh air entered the downcast shaft and passed through the passages of the mine workings before it, in turn, became heated and passed out through the upcast shaft. In this way a constant flow of fresh air was maintained through the mine. The image above shows a laboratory model to illustrate this method of ventilation. It consists of two wide glass tubes projecting from the top of a rectangular wooden box with a removable glass front.

A short piece of candle is lit at the base of one of the tubes.A box comprising two chimneys and a candle. Convection currents draw smoke down one chimney and up the other.

Printer friendly. Fig 1: Typical metal walled chimney box with two candles. Fig 1. Operation This equipment effectively demonstrates convection currents using smoke.

A small 'tealight' type candle is placed inside the box beneath one of the chimneys and lit. The door is closed and the chimneys checked to make sure they are not blocked.

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A rolled up piece of paper towel can be lit and blown out after a few seconds so that it smokes profusely. This smoking paper needs to be held quite close to the top of the other chimney. The lit candle will produce strong convection currents which should draw the smoke down the chimney, through the box and up and out of the chimney above the candle. Placing a black piece of paper behind this equipment allows the smoke to be seen more clearly. Newer types tend to be made of enamelled metal which will remain very hot after use.

Older types may be made from a wooden housing, if you have a wooden type, ensure the candle does not stay lit for too long. A piece of thick metal foil can be attached to the underside of the top of the box to dissipate heat from the candle if desired. Safety Metal housings may remain hot after use. The contents of this page are for information only.These facts are examples of the transfer of heat by convection.

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Unlike conduction, in convection it is the material itself that moves, therefore you can't have convection in a solid. In liquids and gases convection takes place because the hotter, low-density fluid rises taking the heat energy with it - this is called a convection current. The bigger the surface area of an object the more air can move round it in convection currents and the faster it will cool. Think of the motorbike cooling fins.

In the photograph the candle flames are bending inwards. This is because there is an updraft of air at the centre and this is drawing in cold air from the sides pushing the flames towards the centre. You can demonstrate convection by the following simple experiments. Convection in water Fill a beaker with cold water and then carefully drop a few crystals of potassium permanganate into it so that they fall close to one side of the beaker.

Now heat the base of the beaker just under where the crystals have fallen. You can also use the special piece of apparatus shown in the diagram.

convection smoke box experiment

It is a "square " glass tube filled with water. Drop a crystal of potassium permanganate into the top and then heat one of the bottom corners gently. You will see the colour begin to move round the tube going down the limb opposite the heating and then rising up the other side above the Bunsen due to convection currents in the water. Convection in air a simply hold your hand above the bunsen flame. You can easily feel the hot air rising. Light the candle and then hold a piece of smouldering paper or string over the top of the other chimney.

The smoke should be pulled down that chimney and rise up the other chimney with the hot air above the candle. Make a small rotor out of aluminium foil and hold it above a bunsen burner to test the effect of the convection currents in the air.

Convection - Smoke Flow - English - See Air Flow!

What is actually is convection? Convection occurs because the air or other fluid is heated, expands, becomes less dense and so rises through the more dense colder air. Convection The hottest air in a room is near the ceiling. Breezes occur on the coast because of air rising above the land or sea. The outlet for the hot water is at the top of the hot water tank.

The ice box is always at the top of a fridge. Motor cycle engines are air cooled and are fitted with fins. The element in a kettle is near the bottom of the kettle. Some hot water cylinders have two immersion heaters, one small one near the top of the tank and one large one nearer the bottom. Problems 1. Why is it not vital to keep the lid of a chest freezer closed? Why is the ice box always at the top of the fridge? Why do you think that convection is important in a house hot water system?

Why does a coal, fire help to ventilate a room as well as heat it?


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