December 1, 2010
by: Tami O’Connor
The fire syringe sold by Educational Innovations is a wonderfully simple, yet impressive and dramatic demonstration that increasing pressure on a gas increases its temperature. The fire piston, predecessor to the fire syringe was once used as a means of kindling fire in prehistoric Southeast Asia and the Pacific Islands. The apparatus used a hollow cylinder, sealed at one end and open on the other. A piston fit snugly in the cylinder and by sharply compressing the air, the tinder would ignite. This is an example of compression ignition.
This is also the principle behind a diesel engine. Unlike gasoline engines, diesel engines do not have spark plugs. Rather, the upward movement of the piston compresses the fuel vapor and increases the temperature to the point of combustion. That forces the piston down thus turning the drive shaft.
Here is how best to operate a fire syringe:
Place the piston into the mouth of the cylinder and thread the collar back onto the syringe. Place the syringe on a sturdy table. Get a firm grip on the handle and force the piston straight down, FAST AND HARD. The compression of the air causes the temperature of the gas to rise rapidly, igniting the material at the base of the cylinder. If the compression is done too slowly the heat will dissipate before ignition will occur. This can take a little practice, so don’t be discouraged if it doesn’t flash the first time you try it. It may be helpful to prepare a few pieces of toilet paper or cotton fiber in advance. Read the rest of this entry »
April 19, 2010
by: Bennett M. Harris
It never fails. I get the same reaction, whether I present to seasoned physicists, grade level science teachers or even from the most discerning audience I’ve had; a group of fifty – fourth grade students, jaws gape and sounds of oohs, aahs and wows issue forth.
I’ve been in rooms surrounded by hundreds of artificial light sources, from the simplest incandescent bulbs to the most advanced OLED displays, and even so, when a person closes that knife switch and current begins to flow and a simple piece of pencil lead held suspended inside a partially evacuated chamber starts to glow brighter, brighter, and finally white light illuminates the chamber, something happens in the person’s brain. At once they are connected with the wonders that Sir Humphry Davy, Swan, and Edison felt when they experimented with the world’s first electrical light sources. Questions start to form; How does that work? How could we make it last longer? What would happen if we changed the carbon for some other material? All at once, the passive viewer is thinking scientifically, asking questions, and yearning to do more.
I’m talking about “Reinventing Edison: Build your own Light Bulb”, a science kit that I am proud to have designed. I created the kit to be fun and interesting while at the same time integrating history and invention into science and mathematics. The kit is designed to work as a safe, hands-on, inquiry based science experiment for both qualitative and quantitative experiments. But It also works well as an engaging demonstration at the front of the classroom. Read the rest of this entry »