Magnetism

St. Mary's High School, Manhasset, NY

Maglev Train

Maglev II

Television

What's Magnetism?

 Electric Motor

MRI

MRI Part II

Laundry Cleaners 

Computer Disk Drives

Car Alternator

Tape Recorder

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Tape Recorder

Written by: Andrea B.Typed by: Maria D.

 The Meaningful Uses - Part I

Tape recorders are important for many reasons. They are used to store computer data and measurements from instruments in scientific and medical research. They help preserve and reproduce varied forms of information. Tape recorders are also used in almost every household. This device is used as a magnetic tape recording system that serves as a telephone-answering device. People also use the video tape recorder, which records and reproduces an electronic signal containing audio and video information, The tape recorder is commonly used for television productions, intended for re-broadcasting to large audiences. This device replaces live telecasts. Everyday people, doctors, musicians, television studios, and many other people use tape recorders. The tape recorder allows people to record and playback any type of information they need.

Valdemar Poulsen first demonstrated magnetic recording in 1900. He introduced a machine called the telegraph, which recorded speech magnetically on a steel wire. In the following years, researchers in Germany, Great Britain, and the United States developed new types of magnetic recording. The invention of the tape recorder gave composers in the 1950ís an exiting new musical instrument to use for new musical experiences.

The tape recorder records and reproduces sound by keeping electrical signals as magnetic patterns on a plastic tape coated with magnetic oxide. When recording, an imprint is left on the tape when it passes through a recording head. Magnetic recording is used to preserve sounds, pictures and data in the form of electrical signals. Among the wide variety of magnetic recording, the magnetic tape and disk recorders are the most important. These two devices are used to reproduce audio and video signals but also to store computer data.

Tape Recorder - Part II

 The playback head wire is wound several times, making it an electromagnet. When it starts to record, two stereo electric signals are amplified and go to the wound wire. Then, it makes magnetic fields, which cause the particles to become magnets in the tape. When the tape plays back, the particles make a pair of stereo electric signals. The signals then go to the amplifier and a pair of speakers to reproduce the sound.

Tape recording depends on the fact that the particles are lined up by a magnetic field. Recording tape consists of a thin plastic backing, like camera film. One side has particles of magnetic oxide. The oxide side of the tape goes over a small electromagnet, called the recording head, which causes the particles to line up as they move by. This makes a magnetic field. The magnetic field is controlled by impulses from the microphone.

 

Bibliography

The New Book of Popular Science

Grollier Incorporated; 1982

Mc Graw - Hill Encyclopedia of Science and Technology

Mc Graw - Hill Incorporated 1977