Category: Magnetism

Magnetism

Bubble Memory

Bubble Memory

Bubble memory is a sophisticated method of storing data that gets rid of the need for moving parts such as are required in tape machines and disk drives. Data is stored as tiny magnetic...

Magnetic Disk

Magnetic Disk

Since the advent of the personal computer, ever-more compact data-storage systems have evolved. One of the most versatile is the magnetic disk. Hard disks, also called hard drives, store the most data, and are...

Magnetic Tape

Magnetic Tape

On recording tape, particles are magnetized in a pattern that follows the input waveform. Graph A shows an example of an audio input waveform. Graph B shows relative polarity and intensity of magnetization for...

The DC Motor

The DC Motor

A functional diagram of a dc motor Magnetic forces can be harnessed to do work. One common device that converts direct-current energy into rotating mechanical energy is a dc motor. In a dc motor,...

The Relay

The Relay

At A, pictorial diagram of a simple relay. At B, the schematic symbol for the same relay. A relay makes use of a solenoid to allow remote-control switching of high-current circuits. A diagram of...

A Ringer Device

A Ringer Device

A solenoid-coil bell ringer. Above figure is a simplified diagram of a bell ringer, also called a chime. The main functional component is called a solenoid, and it is an electromagnet. The core has...

Permanent Magnets

Permanent Magnets

Permanent magnets are manufactured by using a high-retentivity ferromagnetic material as the core of an electromagnet for an extended period of time. The coil of the electromagnet carries a large direct current, causing intense...

Magnetic Properties of Materials

Magnetic Properties of Materials

There are four important properties that materials can have with respect to magnetic flux. These properties are ferromagnetism, diamagnetism, permeability, and retentivity. Ferromagnetism Some substances cause magnetic lines of flux to bunch closer together...

Electromagnets

Electromagnets

In an electromagnet, the magnetic flux is concentrated in a ferromagnetic rod surrounded by a current-carrying coil. Any electric current, or movement of charge carriers, produces a magnetic field. This field can become intense...

Magnetic Field Strength

Magnetic Field Strength

The overall magnitude of a magnetic field is measured in units called webers (Wb). A smaller unit, the maxwell (Mx), is sometimes used if a magnetic field is weak. One weber is equivalent to...

Causes and Effects

Causes and Effects

Magnets are attracted to some, but not all, metals. Iron, nickel, and alloys containing either or both of these elements are known as ferromagnetic materials. They “stick” to magnets. They can also be made...

The Geomagnetic Field

The Geomagnetic Field

The earth has a core made up largely of iron, heated to the extent that some of it is liquid. As the earth rotates, the iron flows in complex ways. It is thought that...