The basis of operation of electromagnetic machines. Authors Authors and affiliations A. This is a preview of subscription content, log in to check access.
Daniels 1 1. University of Bath UK. Personalised recommendations. Cite chapter How to cite? These coils are constructed with core material and coil windings. When the electromagnets are energized, the train will be levitated by the attractive force between the electromagnets and the coils.
Hence this type of systems needs a large electrical power source, electromagnetic coils lining a guideway and guidance magnets attached to the underside of the train. It is the process of transmitting information from a source to a receiver. This transmission of energy over long distances is carried out through electromagnetic waves at high frequencies. These waves are also called as microwaves or high frequency radio waves.
Suppose in case of mobile phones, sound energy is converted into electromagnetic energy. By using radio transmitters, this electromagnetic energy is transferred to the receiver.
At the receiver these electromagnetic waves are again transformed back into sound energy. Communication System. Depending on the nature of the baseband signal, communication systems can be analog or digital communication systems.
Depending on the nature of transmitting signal, this system is categorized as baseband and carrier communication systems. Electromagnetic fields produced by the time varying sources are propagated through a waveguide or transmission line.
An electromagnetic wave radiation is formed when these electromagnetic fields are propagated away from the sources without any connection or conducting medium to the sources. An electromagnetic spectrum consists of different range of all possible wavelength or frequencies of electromagnetic radiation. These frequency ranges include low frequency, ultra low frequency, medium frequency, high frequency, ultra high frequency, super high frequency etc.
Nowadays electromagnetic fields play a key role in advanced medical equipments such as hyperthermia treatments for cancer, implants and magnetic resonance imaging MRI. RF range frequencies are mostly used in medical applications.
In MRI scans, sophisticated equipment works based on the electromagnetism can scan minute details of the human body. The electromagnetic therapy is an alternate form of medicine which claims to treat disease by applying pulsed electromagnetic fields or electromagnetic radiation to the body.
This type of treatments is used for wide range of ailments such as nervous disorders, diabetes, spinal cord injuries, ulcers, asthma, etc. Why might we want to use an electromagnet rather than a permanent bar magnet? There are two obvious advantages to using electromagnets. Firstly they can be switched on and off.
Complete an electric circuit and a current passes to produce a magnetic field. Switch off the current and the magnetism disappears provided the iron forms a temporary magnet. Also, their magnetic strength can be changed. The strength of the magnetic field around the solenoid can be increased by:. Car scrap-yards use huge electromagnets to lift heaps of crumpled iron and steel. Switch off the current and the object crashes to the ground. In the home, by far the most common use of electromagnets is in electric motors.
Think of all of those bits of electrical equipment with some kind of electric motor: vacuum cleaners, refrigerators, washing machines, tumble driers, food blenders, fan ovens, microwaves, dish-washers, hair driers.
The list is a long one, and when you start thinking more widely about electric motors in cars, lawn-mowers and a whole host of industrial applications, it becomes obvious that this application of electromagnets is extensive and extremely important to our daily lives. The question of how electric motors work builds on the basics of magnetism introduced here, and is usually worked on in later years.
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