Year: 2012

Until the Battle of the Yellow Sea[8] was fought on 10 August 1904, for naval battles of the 1890s the decisive weapon was the medium-caliber, typically 6-inch (152 mm), quick-firing gun firing at relatively short range; naval gunnery was too inaccurate to hit targets at...

The distinctive all-big-gun armament of the dreadnought was developed in the first years of the 20th century as navies sought to increase the firepower and range of their battleships. The majority of pre-dreadnought battleships had a main armament of four heavy guns of 12-inch (305...

The dreadnought was the predominant type of battleship in the early 20th-century. The first of the kind, the Royal Navy’s Dreadnought, had such an impact when launched in 1906 that similar battleships built after her were referred to as “dreadnoughts”, and earlier battleships became known...

The potential health effects of the very low frequency EMFs surrounding power lines and electrical devices are the subject of on-going research and a significant amount of public debate. In workplace environments, where EMF exposures can be up to 10,000 times greater than the average,...

Main articles: near and far field, electromagnetic radiation, virtual particle, dielectric heating, and magnetic induction An EM field that varies in time has two “causes” in Maxwell’s equations. One is charges and currents (so-called “sources”), and the other cause for an E or B field...

Main articles: electrostatics, magnetostatics, and magnetism When an EM field (see electromagnetic tensor) is not varying in time, it may be seen as a purely electrical field or a purely magnetic field, or a mixture of both. However the general case of a static EM...

The behavior of the electromagnetic field can be resolved into four different parts of a loop: the electric and magnetic fields are generated by electric charges, the electric and magnetic fields interact with each other, the electric and magnetic fields produce forces on electric charges,...

In the past, electrically charged objects were thought to produce two different, unrelated types of field associated with their charge property. An electric field is produced when the charge is stationary with respect to an observer measuring the properties of the charge, and a magnetic...

The electromagnetic field may be thought of in a more ‘coarse’ way. Experiments reveal that in some circumstances electromagnetic energy transfer is better described as being carried in the form of packets called quanta (in this case, photons) with a fixed frequency. Planck’s relation links...

Classically, electric and magnetic fields are thought of as being produced by smooth motions of charged objects. For example, oscillating charges produce electric and magnetic fields that may be viewed in a ‘smooth’, continuous, wavelike fashion. In this case, energy is viewed as being transferred...