| Maxwell\'s_Equations Description of Maxwell's equations. |
| Maxwell\'s_Equations_and_Electromagnetic_Waves An overview of Maxwell's Equations and how they determine the speed of light. |
| Negative_Permittivity_and_Permeability_Material The true "left handed" material is described. In this medium, light waves are expected to exhibit a reverse Doppler effect. |
| Paradoxes_of_Modern_Electrodynamics Provides analysis of some modern electrodynamics concepts including peculiarities and «white spots» in the model of an electromagnetic wave. The site is in English and Russian. |
| PowerLabs___Rail_Gun Electromagnetic capacitor powered 20kJ rail gun research. |
| Science_Ebooks_Ezine This site offers a variety of electronics and physics animations and visual aides for teachers or students. |
| Spin_Science Research conducted at the University of Amsterdam utilizing x-ray magneto-optical techniques for the study of thin film and nanometric magnetic systems. |
| Static_Electricity Website by Jeremy Smallwood on static electricity. Describes the physics phenomena, possible electrostatic damages, materials for electrostatic solutions, and standards. Gives advice on solution of co |
| Static_Electricity_Projects Site devoted to projects utilizing static electricity (motors, generators) which are simple enough and can be relatively easily built. |
| Vacuum_Tube_Diode A demonstration of how a vacuum tube diode works. |
| The_Van_de_Graaff_Generator_Website This site includes information on how Van de Graaff Generators work, typical classroom demonstrations, and instructions for building one. |
| VRML_Gallery_of_Electromagnetism Visualization of the electromagnetic field. |
| Wireless_Lab_at_Nizhny_Novgorod_University Laboratory of Physical Fundamentals and Technologies of Wireless networks at Nizhny Novgorod State University, Russia. |
| Wondermagnet_com Images of magnets and their uses, experiments, a discussion board about magnet-related topics, and an elementary primer on magnetism and magnetic physics. |
| X-ray_Optics_and_Microscopy_at_Stony_Brook Research describing use of coherent soft X-rays for optics experiments, including Fresnel zone plates, to produce the smallest focused spot of electromagnetic waves for studies of biological and mater |
| NSSDC__Venus From NASA's photo gallery. |
| Planet_Venus_-_overview_and_pictures Illustrated guide to Venus. Contains description, facts, statistics and a brief history. |
| Venus From The Nine Planets. |
| Venus NASA's Windows to the Universe. |
| Venus Details on this planet. |
| Venus From "Views of the Solar System". |
| Venus Facts, early knowledge and history of man's exploration of Venus. |
| Venus_Basic_Information Summary articles and related links. |
| Venus__Earth\'s_troubled_sister Although it looks a lot like Earth, it's actually dramatically different. |
| Welcome_to_the_Planets__Venus Planetary profile and vital statistics, some pictures. |
| ACalendar_com The calendar has many options with a standard monthly interface, including sunrise, sunset, and Moon phases. |
| Annus_Novus_Decimal_Calendar A proposal for a non-sectarian, culturally neutral calendar system. |
| Astro_Portal_-_CalSKY The worldwide interactive online astronomical/space calendar and calculator - for friends of astronomy, as well as astronomers. |
| Astronomical_Time_Keeping Extensive descriptions of many astronomical time keeping systems, with information on time zones and Julian day numbers. |
| Astronomy_by_JavaScript__Sun_Calculators_and_More Applets related to calendars and keeping time, including sidererial time. |
| Astronomy_Calendar Features different views of the night sky, constellations, stars, planets, and other celestial wonders. |
| Blue_Moon_Myths Second full moon in a month, or third full moon in a single season? |
| Britannica_com_-_Clockworks__From_Sundials_to_the_Atomic_Second Britannica.com explores the history of timekeeping, from sundials to cesium atomic clocks. |
| The_Calendar,_Leap_Years_and_the_Year_2000 An explanation of the calendar including the origin of the day, week, month and year. |
| Calendar_Studies Articles on the Gregorian and Julian calendars, the ISO date format, the Julian day number system, the Maya calendar, the Goddess lunar calendar, the Liberalia Triday Calendar and C functions for date |
| Calendars_through_the_Ages History and FAQs of calendars, from ancient Rome to outer space. Including Julian, Gregorian, Jewish, Islamic, Chinese, and Mayan. |
| Calendopaedia The Encyclopaedia of Calendars. |
| Calendrical_Calculations Published by Cambridge University Press. Gives a unified algorithmic presentation of the Gregorian, ISO, Julian, Coptic, Ethiopic, and Islamic civil calendars. |
| The_Chinese_Calendar The mathematics of the Chinese calendar. Explains the rules for the Chinese calendar. |
| The_Difference_Between_the_Millennium_and_Year_2000 Questions and answers to satisfy the hearts of true millennium buffs. |
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Please copy/paste the following text to properly cite this HowStuffWorks article:Brain, Marshall. "How Compasses Work." 01 April 2000. HowStuffWorks.com. <http://adventure.howstuffworks.com/compass.htm> 02 December 2008. Inside this Article Introduction to How Compasses Work Creating Your Own Compass Lots More Information See all Hiking articles Adventure Videos 
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A compass will always point toward the North Pole. See more pictures of compasses and magnets. No matter where you stand on Earth, you can hold a compass in your hand and it will point toward the North Pole. What an unbelievably neat and amazing thing! Imagine that you are in the middle of the ocean, and you are looking all around you in every direction and all you can see is water, and it is overcast so you cannot see the sun... How in the world would you know which way to go unless you had a compass to tell you which way is "up"? Long before GPS satellites and other high-tech navigational aids, the compass gave humans an easy and inexpensive way to orient themselves. But what makes a compass work the way it does? And why is it useful for detecting small magnetic fields, as we saw in How Electromagnets Work? In this article, we will answer all of these questions, and we'll also see how to create a compass from scratch! A compass is an extremely simple device. A magnetic compass (as opposed to a gyroscopic compass) consists of a small, lightweight magnet balanced on a nearly frictionless pivot point. The magnet is generally called a needle. One end of the needle is often marked "N," for north, or colored in some way to indicate that it points toward north. On the surface, that's all there is to a compass. The reason why a compass works is more interesting. It turns out that you can think of the Earth as having a gigantic bar magnet buried inside. In order for the north end of the compass to point toward the North Pole, you have to assume that the buried bar magnet has its south end at the North Pole, as shown in the diagram at the right. If you think of the world this way, then you can see that the normal "opposites attract" rule of magnets would cause the north end of the compass needle to point toward the south end of the buried bar magnet. So the compass points toward the North Pole. 
To be completely accurate, the bar magnet does not run exactly along the Earth's rotational axis. It is skewed slightly off center. This skew is called the declination, and most good maps indicate what the declination is in different areas (since it changes a little depending on where you are on the planet). The magnetic field of the Earth is fairly weak on the surface. After all, the planet Earth is almost 8,000 miles in diameter, so the magnetic field has to travel a long way to affect your compass. That is why a compass needs to have a lightweight magnet and a frictionless bearing. Otherwise, there just isn't enough strength in the Earth's magnetic field to turn the needle. 
The "big bar magnet buried in the core" analogy works to explain why the Earth has a magnetic field, but obviously that is not what is really happening. So what is really happening? Up NextCompass QuizHow GPS Receivers WorkHow the Bermuda Triangle WorksNo one knows for sure, but there is a working theory currently making the rounds. As seen on the above, the Earth's core is thought to consist largely of molten iron (red). But at the very core, the pressure is so great that this superhot iron crystallizes into a solid. Convection caused by heat radiating from the core, along with the rotation of the Earth, causes the liquid iron to move in a rotational pattern. It is believed that these rotational forces in the liquid iron layer lead to weak magnetic forces around the axis of spin. It turns out that because the Earth's magnetic field is so weak, a compass is nothing but a detector for very slight magnetic fields created by anything. That is why we can use a compass to detect the small magnetic field produced by a wire carrying a current (see How Electromagnets Work). Now let's look at how you can create your own compass. 
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Related ContentExplanationsHow GPS Receivers WorkHow Electromagnets WorkHow Gyroscopes WorkExpert ReviewsGPS Device Reviews Prices: Compasses 
Suunto A-30L Compass The Suunto A-30L Compass includes a luminous bezel and declination correction scale to cover all the bases for recreational backpacking and scouting. ...$19.22 
BQM SURVIVAL WRIST COMPASS Liquid-filled precision compass is protected in a sturdy non-magnetic case and slides on most wristbands. This handy accessory navigation backup compa...$5.99 
Ritchie Sport Angler Compass (Bracket-mount) Bracket-Mount - Big compass performance in a small package. Bracket-mount unit features no-glare, gray finish and distinctive, easy-to-read graphics. ...$52.99 
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