A compass uses a magnet that points north according to the Earth's natural magnetic field. In many compasses, the indicator is a magnetic needle mounted on a spindle that allows it to swing freely, while in others there may be multiple magnets and a liquid base to dampen oscillations.Know More
Earth has two magnetic poles, one near the northernmost point on the globe and one near the southernmost point. The pull of these poles is strong enough to influence magnets everywhere on the planet. The magnet inside a compass is mounted so it may swing freely, and it naturally falls in line with the Earth's magnetic field, indicating north.
Technically, the northern magnetic pole of the Earth is the south pole of the Earth's magnetic field because it attracts the "north" end of magnets. Opposite poles of magnets attract, and the north pole of a magnet is attracted to the north magnetic pole, which is the south pole of the magnetic field.
The magnetic poles do not totally correspond with the northernmost and southernmost points on the globe, and they can wander over time, slightly changing the official direction of magnetic north. In addition, the magnetic field of the Earth has weakened and grown stronger many times in history, and on occasion, the poles have even swapped places.Learn More
Pumice is an igneous rock formed by the rapid cooling and depressurization of volcanic magma with a high gas content. It is characterized by a large amount of vesicles formed from gas bubbles in the magma.Full Answer >
A rock identification key is a system used to identify rocks. It's usually in the form of a chart or table with several common descriptive properties of rocks.Full Answer >
Crustal plates are large sections of the outer layer of the Earth's surface that move along convection currents in the mantle. There are 10 major plates on the surface, and the tectonic forces behind their movement create earthquakes, volcanoes and tidal waves.Full Answer >
Hurricane Andrew began as a tropical wave that crossed the west coast of Africa into the tropical North Atlantic on August 14, 1992. Two days later, after it passed just south of the Cape Verde islands, the wave became a tropical depression. Tropical Storm Andrew formed August 17 and became a hurricane three days later due to vertical wind shear. The hurricane caused 23 deaths in the United States.Full Answer >