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Science Experiments With Fans and Gas

Fans offer a simple, fun and instructive way to interact with gases. They are particularly well-suited to experiments with young children because of their easily understood principles. Exploring this field can also offer more challenging experiments for older students. Ultimately, the physics involved in the flow of air can be quite complex, allowing as much exploration as a student has curiosity.

Gases and Fans
- The air around us is in a state of matter called gas. Any experiment with a fan is really an experiment with this state of matter because it will demonstrate how a gas behaves. Like liquids such as milk or water, gases are fluid, meaning that they take the shape of whatever container they are in. But unlike liquids, gases will expand to fit whatever container they are in -- like a small puff of smoke dissipating in a large room. Fans are simply solid blades used to push a gas around.
Make a Fan
- A type of fan called the axial-flow fan, such as a desk or ceiling fan, pushes air parallel to its axle. Such a fan can be built at home with varying levels of difficulty. Young children might insert stiff paper blades into slits cut by an adult into a cork. Attach a skewer to the cork as an axle. Call attention to the angle of the blades. They must be mounted at a diagonal to the shaft so that they move the air in the same direction as the shaft points. If they are mounted parallel to the shaft, they will paddle the air away from the fan in all directions. If they are perpendicular to the shaft, they will slice through the air like a circular saw, without creating much wind.
The Power of Moving Air
- The air around us is transparent, but fans can show us how the molecules of this air are acting by pushing them against objects we can see. This science can be demonstrated with something as simple as taping a stick to small piece of paper and waving it at a dried leaf. The leaf will move, demonstrating how the fan is pushing the air, creating wind. This principle can make a game, too. Place a powered fan midway between the students and a wastebasket, and ask them to toss crumpled bits of paper into the wastebasket. When the paper balls encounter the column of moving air created by the fan, they will be blown off target.
Evaporation
- A simple experiment in evaporation can be made with a fan and two sponges. Soak the sponges with water. Leave one sponge in an undisturbed spot. Place the other in front of an operating fan. Ask the students which sponge will dry out first. The fan will increase the rate of evaporation, or the conversion of the water from liquid to gas, which is carried away with the surrounding air.
Wind Generating Electricity
- Wind turbines are like fans, using wind to generate power.
  
  An intriguing and slightly more complex experiment involves a fan and a second propeller. Attach a paper pinwheel or other propeller to a small electric motor and connect the motor with wire to a small light bulb, such as one found in a toy. Use the wind from a powered fan to drive the blades of your pinwheel. The spinning motion will cause the motor to generate a small amount of electricity, lighting the bulb. This is the same principle at work in industrial-sized wind generators, which are essentially axial fans driven by the wind.

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