This applet simulates the reaction a compass has to a nearby magnetic field.
To try this
simulation:
Left-click and drag your mouse to move the magnet.
What's Going On?
The compass needle is a small magnet sensitive to the effects of external magnetic forces. Normally the compass needle lines up with the earth's magnetism. But any magnet or piece of iron near the compass will affect it.
The Attitude Gyro is an aircraft instrument that tells the pilot the direction her aircraft is flying in when clouds hinder the use of landmarks as guidance. A gyroscope inside maintains its direction. No matter how the aircraft is positioned the Attitude Gyro will show the aircraft's current position.
The Laser Gyro is a new technology for maintaining direction. A laser inside shines through a coil of light pipe (optical fiber). As the laser gyro is rotated, the light in the coil takes more time to travel in the direction of rotation than in the opposite direction. Sensors in the gyro detect this time lag and use this to determine in which direction the gyro is turning.
There's More!
GPS provides much more information than that given by a compass. A GPS unit tells within inches where it is in longitude, latitude and altitude. The unit is a radio receiver getting signals from several satellites orbiting the earth. The signals contain information about each satellite's position and the time the signal was sent. The GPS unit uses this information to calculate its location on the earth.
GPS technology is being used in more day to day applications, such as in on-board car navigation systems and is becoming more affordable as are other types of technology. Someday your children may have GPS units in their shoes so you'll always know where they are!
