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Name: Jose
Status: student
Grade: 9-12
Location: TX
Country: N/A
Date: 5/10/2005

How is light produced? (How can I explain it to my 4th grade brother?)


First, how light is really produced: Electrons, and other charged particles, get too much energy. You can almost say they vibrate too much. To release this extra energy, they release waves of light. In some ways, it is like vibrating the end of a string or spring. The extra energy from your hand travels through the string or spring as a wave. Because it happens at the level of individual particles, you need quantum physics to get precise. When you heat something, the molecules vibrate. Now, the vibrating charges in the atoms release waves of energy. The object glows. A light bulb works the same, but the electricity causes the heat. Fluorescent bulbs do not even heat up. The energy goes straight to the electrons.

Now, how to explain it to your brother: If he knows about electrons and atoms, this should work. If not just do not mention the atoms. The material gets extra energy and emits waves. Demonstrate waves on a long narrow spring or a long heavy string. In either case, let him watch a wave pulse travel along from one end to the other.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College

There are many ways to produce light.

Chemically (a fire).

Electrically (a spark).

By heating an object up (an electric stove or a toaster).

Mechanically (strike a flint and steel to produce a spark).

All of these methods involve converting one form of energy (chemical, electrical, thermal) into another (light).

Greg Bradburn

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