Author: Lou Bloomfield

How does a computer chip work?

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How does a computer chip work? — JM, Austin, TX

A computer chip is also known as a digital integrated circuit. It is typically a thin wafer of silicon, cut from a single crystal of that element. The surface of the wafer has been chemically modified and it has had intricate patterns of aluminum wires and other structures cut and deposited photographically on its surface to form enormous numbers of transistors and other special structures. Each of these transistors is an electronically controllable switch. A tiny adjustment in the electric charge on the control element of one of these transistors—its gate—can dramatically alter that transistor’s current carrying ability. These transistors work together to perform task that range from remembering one bit of information to multiplying two huge numbers together. The millions of transistors on a typical computer chip are able to perform extremely complicated tasks, as we see everyday in modern computers.

Does the creation of life and the theory of evolution violate the laws of thermo…

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Does the creation of life and the theory of evolution violate the laws of thermodynamics? — BY, Liverpool, NY

While the laws of thermodynamics forbid an overall increase in the order of the universe and while life is an example of significant order, the laws of thermodynamics don’t forbid some parts of the universe from becoming more orderly at the expense of other parts of the universe becoming less orderly. Living organisms are consumers of order and exporters of disorder—they derive their order by creating disorder elsewhere. You eat highly ordered chemicals in your food and you eliminate those chemicals in much more disordered forms latter on. You also emit heat, the most disordered form of energy. Thus thermodynamics has no problem with the ongoing existence of life; it simply requires that living organisms consume order and we are doing just that at a furious pace.

As for the creation of life, that could have been a random event and thermodynamics permits random events. Improbable events do occur—people win the lottery, lightning strikes twice, two snowflakes are occasionally alike—and the creation of life could have been one of those unlikely but not impossible events. Once the simplest organism had assembled itself by chance, it could then begin the process of consuming order and exporting disorder.

What exactly are gravity waves and how are they measured?

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What exactly are gravity waves and how are they measured? — AY, Wayne, PA

Gravity waves are deformations of space/time that propagate through space at the speed of light. While many motions of matter and energy are thought to emit gravity waves, those waves are normally extraordinarily weak. The only sources of detectable gravity waves are probably collapsing and colliding stars. Careful studies of the dynamics of binary star systems have shown that they also emit reasonably strong gravity waves, but those waves haven’t been detected directly.

The two classes of gravity wave detectors currently in development or operation are large cryogenic bar detectors and laser interferometric detectors. A cryogenic bar detector tries to observe gravity waves by looking for vibrational excitations of huge metal bars. When a strong gravity wave passes through one of these bars, it should excite various vibrations in the bar that can be detected by sensitive motion sensors. A laser interferometric detector tries to observe gravity waves by looking at distance changes in the arms of a laser interferometer—a huge mirror system with laser beams bouncing back and forth within it. When a strong gravity wave passes through the mirror system, it should change the spacings of the mirrors enough to cause variations in the optical characteristics of the interferometer (for more info, see www.ligo.caltech.edu). So far, no gravity waves have been observed definitively.

How much electric current is there in an automobile spark plug?

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How much electric current is there in an automobile spark plug? — DG, Brooklyn, NY

Without measuring it directly, I would guess that the current passing through a spark plug during a spark is about 10 milliamperes. I base that guess both on a calculation—assuming sensible values for the energy, voltage, and duration of the spark—and on my experience with electric sparks. If I have a chance to measure the current directly—I have the equipment but not the time—I’ll put a more specific value here.

How does a roller coaster work?

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How does a roller coaster work?

A roller coaster is essentially a gravity-powered train. When the chain pulls the train up the first hill, it transfers an enormous amount of energy to that train. This energy initially takes the form of gravitational potential energy—energy stored in the gravitational force between the train and the earth. But once the train begins to descend the first hill, that gravitational potential energy becomes kinetic energy—the energy of motion. The roller coaster reaches maximum speed at the bottom of the first hill, when all of its gravitational potential energy has been converted to kinetic energy. It then rushes up the second hill, slowing down and converting some of its kinetic energy back into gravitational potential energy. This conversion of energy back and forth between the two forms continues, but energy is gradually lost to friction and air resistance so that the ride becomes less and less intense until finally it comes to a stop.

How do fruit machines work? Do they operate on a fixed mathematical model which …

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How do fruit machines work? Do they operate on a fixed mathematical model which governs payouts using probability or are they totally random? — TS, Norfolk, UK

I assume that you are referring to the gambling machines that spin several wheels when you pull a lever and that pay you amounts that depend on the patterns of symbols that show on the faces of the wheels when they stop. While the final arrangement of symbols that appear on such a machine when it stops is entirely random, the patterns that pay and the amounts they pay are calculated to ensure a slight financial advantage for the house. The mathematics of probability is well developed for such gambling machines and it’s relatively simple to determine what fraction of your money you should expect to lose if you play the game for a very long time. If you do play long enough to sample the full statistics of the game, you are certain to lose money. It’s only if you play briefly that you can take advantage of statistical fluctuations to leave with more money than you had when you started.

Is there a device that would provide a variable output of radiated energy in the…

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Is there a device that would provide a variable output of radiated energy in the infrared that would be obtainable to experiment with? — NAT, Marion, SC

You can produce a broad range of infrared lights with a heat lamp. A heat lamp looks very dim because most of the thermal radiation it emits is in the infrared portion of the electromagnetic spectrum. Just attach the heat lamp to a normal light dimmer and you’ll be able to vary its infrared output over a wide range of intensities. Its frequency range will also shift farther away from the visible as you lower its temperature by turning down the dimmer. If it produces more visible light than you want, you can put a filter in front of it that absorbs visible light while permitting infrared light to pass. Such filters are certainly available from filter companies such as Hoya or Corning but cheaper versions (perhaps even plastic filters) may be found through scientific supply companies.

Could you give me the formula for figuring the wavelength of an ultrasound wave?…

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Could you give me the formula for figuring the wavelength of an ultrasound wave? — BH

The wavelength of any wave is equal to the speed of that wave divided by its frequency. In air, the speed of sound is about 330 meters per second, so an ultrasonic wave with a frequency of 50,000 cycles per second would have a wavelength of about 6.6 millimeters. Since sound travels much faster in liquids or solids, the wavelengths would be larger than in air.