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Many people wear glasses to help them see, but how do the lenses in the glasses work? Bob Symes demonstrates the differences in the images produced by flat, convex, and concave lenses. He shows how a lens bends light according to the thickness and direction of its curve. (8 minutes)



 
    

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Part of the Series : The Way Things Work
     


Only available in the US and Canada.




What Magnets Do

A compass needle points North because the Earth has a magnetic force that attracts the metal in the needle. Bob Symes shows what happens to the compass needle if a wire with an electric current is placed next to the compass. He proves that this princ...(more details)
 
How Batteries Work

Although batteries may look complicated, they are as simple as lemons. Bob Symes uses this fruit as the source of electrolytes-a basic component of all batteries. He attaches two dissimilar metal rods (one zinc, one copper) to a lemon and then measur...(more details)
 
How Light Changes Color

What produces color, and why does a color look different when viewed through lenses of different colors? Bob Symes investigates the mysteries of color with several simple experiments. By spinning a disk that has been painted with equal segments of bl...(more details)
 
Why Light Bulbs Glow

Bob Symes proves that air (oxygen) must be present for an object to burn. A light bulb is a glass "envelope" surrounding a vacuum. When electricity passes through the wires inside the bulb, the wires get hot and glow, but they do not burn because the...(more details)
 
How Telephones Work

We speak into the telephone; we hear the voice of the caller, but how do the voices travel from one telephone to the other? Bob Symes opens up a telephone receiver to find the answer. A microphone made of loosely packed carbon granules changes the el...(more details)
 


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