Decibel

a unit for measuring the level of sound which has the symbol dB.

Taken from Dictionary of Science

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The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power or intensity) relative to a specified or implied reference level. Since it expresses a ratio of two quantities with the same unit, it is a dimensionless unit. A decibel is one tenth of a bel, a seldom-used unit.

The decibel is widely known as a measure of sound pressure level, but is also used for a wide variety of other measurements in science and engineering (particularly acoustics, electronics, and control theory) and other disciplines. It confers a number of advantages, such as the ability to conveniently represent very large or small numbers, a logarithmic scaling that roughly corresponds to the human perception of sound and light, and the ability to carry out multiplication of ratios by simple addition and subtraction.

The decibel symbol is often qualified with a suffix, which indicates which reference quantity or frequency weighting function has been used. For example, "dBm" indicates that the reference quantity is one milliwatt, while "dBu" is referenced to 0.775 volts RMS.

The definitions of the decibel and bel use base-10 logarithms. For a similar unit using natural logarithms to base e, see neper.

Taken from Wikipedia

Ultrasonic

a term used to describe sound waves that are inaudible to humans as they have a frequency above 20kHz. Although the human ear is incapable of detecting such a high FREQUENCY, some animals, such as dogs and bats, can detect ultrasonic waves (also known as ultrasound). Ultrasound is used wisely in industry, medicine and research. For example, it is used to detect faults or cracks in underground pipes and to destroy kidney stones and gallstones. The most recent development in ultrasonics is their use in chemical processes to trigger reactions involved in the production of food, plastics and antibiotics. Ultrasonics make certain chemical processes safer and cheaper as they eliminate the need for high temperatures and expensive catalysts.

Taken from Dictionary of Science

Radiation

the giving out of energy from a source, which may be in the form of ELECTROMAGNETIC WAVES (radio, light, X-rays, infrared rays, etc.), particles or sound waves.

Taken from Dictionary of Science

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In physics, radiation describes any process in which energy emitted by one body travels through a medium or through space, ultimately to be absorbed by another body. Non-physicists often associate the word with ionizing radiation (e.g., as occurring in nuclear weapons, nuclear reactors, and radioactive substances), but it can also refer to electromagnetic radiation (i.e., radio waves, infrared light, visible light, ultraviolet light, and X-rays) which can also be ionizing radiation, to acoustic radiation, or to other more obscure processes. What makes it radiation is that the energy radiates (i.e., it travels outward in straight lines in all directions) from the source. This geometry naturally leads to a system of measurements and physical units that are equally applicable to all types of radiation. Some radiations can be hazardous.

Taken from Wikipedia

Retirement at 16?

By Ally Azzarelli

My earliest penny-counting days date back to the tender age of 7.

Silly as it may sound, I attempted to charge my family to use our bathroom. I hung up a bread bag on the doorknob and solicited my parents for donations. The venture lasted about an hour.

As the years progressed I moved on to selling three or four tickets for dance performances. Those weekly dancing and baton-twirling classes had finally been put to use! I'd round up my father's albums, put on my sequined dance costume and perform a talent show featuring my 3-year-old brother and me.

Truthfully, I can't think of a single show where my brother ever got his one-liner correct! The minute he saw my mother clapping her hands and "wowing," he was off climbing into her lap.

Most kids spent their summers on the beach or in the backyard pool. I, however, could always be found behind a picnic table on our front lawn.

Lucky for me, it was on one of the busiest streets in town. I can remember countless hot summer afternoons spent trying to "rake in a few bucks" selling lemonade or iced tea.

If it wasn't pouring sugary drinks, it was conducting a book and magazine sale. Then, as the months passed, it would be raking leaves, which would soon change into lucrative snow shoveling.

As I got older my strategies proved more successful. Too young to baby-sit alone, I decided to transform our basement into "Allyson's Play School."

Such an idea could not be complete without a strong curriculum including arts and crafts, snack time and show and tell. We even had a sports day (with three ribbons) in the backyard. The profits weren't much, but it was a big step from sweating it out behind an iced-tea stand.

What baffles me is what I--then a child of 10--ever wanted with so much pocket change. I can't recall saving it. In addition to the generous allowance doled out by my parents every Friday, I was always scheming new plans.

My next idea is one that I won't forget. While awaiting the age at which I could be legally employed, 16, I devised a final plan. At that time I was a fanatic of the '60s group, the Monkees. I arranged to put together a newsletter.

Thanks to numerous classified ads and the hundreds of fliers passed out at their beach concerts, this "fanzine" was subscribed to by 168 people across the United States. Charging as little as $5 a year for the quarterly newsletter, I made next to nothing after tallying up photocopying costs and postage stamps.

My motto at that age was: "Wow, I'm havin' fun and meeting new people. Who cares if I'm only making $40 a year?"

But now that I am 16 I should be ready for the business world, right? Wrong!

What really baffles my family is that now that I'm legally permitted to get a part-time job, I prefer not to.

Finally I can go confidently to the candy store owner for a position that has not been filled for months. Why haven't I?

Why is it that now when spending money is so important to a teenager, I am making do with an almost empty bank account? Has a new-found laziness taken over my mind? Not at all, I just feel like I'm ready for a hard-earned retirement plan!

Editor's Note: The author, 16, is from North Valley Stream, New York

Taken from Youth 90 magazine