Three examples of electromagnetic devices are:
1. Loudspeaker
2. Tape recorder
3. Electric moto
Questions about how fast the earth--or anything, for that matter--is moving are incomplete unless they also ask, "Compared to what?" Without a frame of reference, questions about motion cannot be completely answered.
Consider the movement of the earth's surface with respect to the planet's center. The earth rotates once every 23 hours, 56 minutes and 4.09053 seconds, called the sidereal period, and its circumference is roughly 40,075 kilometers. Thus, the surface of the earth at the equator moves at a speed of 460 meters per second--or roughly 1,000 miles per hour.
As schoolchildren, we learn that the earth is moving about our sun in a very nearly circular orbit. It covers this route at a speed of nearly 30 kilometers per second, or 67,000 miles per hour. In addition, our solar system--Earth and all--whirls around the center of our galaxy at some 220 kilometers per second, or 490,000 miles per hour. As we consider increasingly large size scales, the speeds involved become absolutely huge!
The galaxies in our neighborhood are also rushing at a speed of nearly 1,000 kilometers per second towards a structure called the Great Attractor, a region of space roughly 150 million light-years (one light year is about six trillion miles) away from us. This Great Attractor, having a mass 100 quadrillion times greater than our sun and span of 500 million light-years, is made of both the visible matter that we can see along with the so-called dark matter that we cannot see.
Each of the motions described above were given relative to some structure. Our motion about our sun was described relative to our sun, while the motion of our local group of galaxies was described as toward the Great Attractor. The question arises: Is there some universal frame of reference relative to which we can define the motions of all things? The answer may have been provided by the Cosmic Background Explorer (COBE) satellite.
In 1989, the COBE satellite was placed in orbit about the earth (again, the earth is the frame of reference!) to measure the long-diluted radiation echo of the birth of our universe. This radiation, which remains from the immensely hot and dense primordial fireball that was our early universe, is known as the cosmic microwave background radiation (CBR). The CBR presently pervades all of space. It is the equivalent of the entire universe "glowing with heat."
Maglev Trains, Hard Drives and MRIs
Electromagnets help maglev trains function and move, but they also help create the magnetic field of a medical magnetic resonance imager to capture images inside the body not viewable by X-ray machines or other means. A miniature electromagnet inside the read-write head, reminiscent of a record player’s arm and needle, magnetizes individual sectors of the magnetic disk and writes the information in binary code to save it. To create the binary code, 0 or 1, the read-write head simply changes direction, driven by the electromagnet. The hard drive uses the same head to interpret the information written to the disk.
Household Electromagnetic Devices
The solenoid valve inside washing machines that turns water off or on is a type of electromagnet. Garbage disposals, microwave ovens and induction cooktops all have electromagnets inside them. Tape recorders, VCRs and DVD players also use electromagnets to record the data.