Although we can't necessarily see electricity, we can measure it by its effects. An ampere, or amp, represents the amount of current in a circuit. Voltage is defined scientifically as the circuit's "potential difference," and can be seen as the amount of "pressure" that drives electricity in a circuit. Watts are a measure of the use of electrical power, and one watt is equal to one volt multiplied by one amp.

In this case it is helpful to use an analogy to help us understand how each of these terms relate to each other. One commonly used analogy is that of the garden hose. The water pressure in the hose is like the voltage, and the amp value is like the volume of water flowing through the hose. The wattage, then, is the total amount of water that comes out of the hose, per unit of time.

If we replace the hose in the above analogy with an electrical wire, it is simple to see how they relate. In an electrical circuit, the voltage may be 220, as it is in most electrical outlets in all the world except the United States and other few countries. Most appliances are meant to run on this voltage, although each operates at different amp levels, and therefore at a different wattage.

An appliance which uses a large amount of current, such as an electric stove, may be on a separate circuit with a higher voltage. There must be more pressure -- or voltage -- to supply the needed amps to the appliance, because it has a higher wattage. In other words, it uses up more current, or amps, per unit of time, than another appliance. Without the higher voltage, it wouldn't run, because it would be "starved" for the amps it needed to be able to operate.

Another electrical term that helps tie together the other three is the ohm, which is a unit of electrical resistance. Going back to the garden hose analogy, if the hose has a larger diameter, more water will be able to flow through. A circuit with a high resistance value, expressed in ohms, is able to carry fewer amps than one with lower resistance, regardless of the voltage. If a high voltage encounters high resistance, the amount of possible amps in the circuit will be very low -- not much water will get through a narrow hose, no matter how high the pressure is.

Electrical consumption is measured in watts, or watt-hours, and this is the basis on which a power company bills a customer for electrical usage. For convenience, power companies measure consumption in a unit called a kilowatt-hour, which is the equivalent of using 1000 watts of power for one hour. The average household uses hundreds of kilowatt-hours per month.

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Biometrics are used to identify people based on their biological traits. This growing technological field has deep implications because proving identity is becoming an integral part of our daily lives. To uncover the prevalence that biometrics could attain, let us consider an ordinary day of Thomas.

Thomas wakes up in the morning, and checks his email on his computer. His service provider requires that Thomas confirm that it is he that is checking his account; instead of entering a username and password, he presses his thumb against a biometric scanner on his keyboard. The system confirms that it is, in fact, Thomas and grants him access to his messages. On his way to work, he enters his car but instead of using a key to identify him as the owner of the vehicle, another biometric scanner checks his fingerprint to confirm that he has the permission to enter.

A biometric hand-recognition device confirms that it is Thomas and allows him entrance to the building at work. Thomas' work computer uses a voice-recognition system that requires him to say a short phrase; it recognizes him and confirms that he has permission to access all programs and files on the computer network.

For lunch, Thomas takes a short trolley ride with some colleagues to a nearby restaurant. Upon entering the trolley, a biometric face-recognition camera recognizes him and automatically bills his bank account. At the restaurant, he pays by 'credit card' but instead of using an actual card, he presses his thumb against a portable biometric scanner. No signature is required and he is authenticated almost immediately. On his way home from work, he stops at the library to pick up a book, and he checks it out with a biometric retina scan instead of a library card.

It is evident that our identity is frequently required; For the time being we use a wide assortment of methods to verify our identity: usernames, passwords, signatures, keys, cards etc. Biometrics allow us to authenticate ourselves with things that we carry with us wherever we may go, such as our hands, eyes, voices, faces, fingerprints etc. In addition to the convenience, biometrics can be much more effective; a key or card, for example, can fall into someone else's hands. The promise of ease and increased security are perhaps biometric's most appealing features.

The downside of all of the benefits of biometrics is personal privacy. If we are going to be identified at various points during the day, will large companies, the government or other institutions track our behaviors and use this data in unanticipated or invasive ways? These questions must be addressed before biometrics have the chance of pervading our daily lives.

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Digital cameras have changed the way photographs are taken and stored. With so many models of digital cameras on the market and in so many different price ranges, it can be difficult to know what to look for when buying one. Basically, there are three factors to consider: resolution, storage capacity, and special features for picture taking and storage.

The resolution of the photographs taken with a digital camera is measured in pixels. The greater number of pixels or dots per inch, the higher the resolution of the finished photograph will be. Digital cameras generally range from 2.0 megapixels to 5 and above. The next generation of digital cameras have higher and higher resolutions as consumers are looking for detail and color accuracy in their images. Older digital technology used under 2.0 megapixels.

Since film is not used in digital photography, the images are stored on internal disks in the camera. Most mid-priced digital cameras do not contain very much storage space and this requires users to download their pictures to their computer before snapping more shots.

More memory can be added to the interior of the camera, just like in a computer. A less expensive method is to add memory by using a small card that pops into the camera. These disks can be purchased with capacities between 64MB all the way up to 2 gigabytes. Larger disks can can hold hundreds of pictures at their highest quality!

Digital cameras come with an assortment of options and features. Some digital cameras can use wide-angle and telephoto lenses for added flexibility. Also when buying a digital camera, it is important to look at how easily the photos can be off loaded to a computer for storage or sharing and how easy they are to print. Some digital cameras come with docking systems that easily transfer the digital images to the computer. The images can then be modified using special editing software, stored to the hard drive or CD-ROM and even emailed.

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An iDog® or any type of iPet, such as iFish or iCat or even the iPenguin, is a clever children’s toy that allows you to use your MP3 player in a very different way. These little animals, which are made of hard plastic and come in a variety of colors, interact with music and will "dance" when they are either plugged into an MP3 player or placed next to a loud speaker. The toys also respond to things like being petted, and are similar in some ways to toy predecessors like Furbies®. The latest version, the iDog Amp’d has more interactive features, even sulking if you don’t allow it to listen to music regularly.

Though one might hope that the iDog, made by Hasbro®, would really do some serious dancing, the toy is a bit more passive. It may shake its head a little, raise its ears up and down, and tap its foot, but it won’t be dancing all over your table or floor. Its principle use, which can be especially helpful in the Amp’d version is as a speaker so you can play your MP3 player without earphones. The earliest versions of iPets did not have stereo sound, so they weren’t necessarily for music aficionados. Amp’d versions of the toy feature stereo sound, about equivalent to an inexpensive boom box, and often good enough for kids who’d like to share music with friends.

Volume on the toy is adjustable, usually by moving the dog’s tail up and down. You can also set the volume on the MP3 player lower if you’d like to turn down the Amp’d iDog. The Amp’d version does tend to play at a higher volume than others around you might appreciate, so it takes a little adjusting. You can also purchase iPets in a variety of colors. Some lean toward the distinctly feminine in color and others are more unisex in color.

Age recommendations for the toy are eight years and up, and it does take careful reading of the instructions to get the most out of any iPet. Kids who are not techies and who don’t read directions well may need to get help from parents at first to get their iDog to respond appropriately, and even parents should read any accompanying instructions carefully.

Price is definitely one of the most likeable features about the toy. While you can spend quite a bit to get docks or stereo systems to accommodate your MP3 player, the Amp’d iDog can retail on sale for as little as $20 US Dollars (USD). When not on sale, the average price of the toy is still under $30 USD, and you might want to do some comparison shopping for the best price. Do expect to use batteries aplenty if you use your iPet frequently. Though the pet only takes two AA batteries, you still might want to consider rechargeable batteries if you find yourself using the iDog all the time.

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