Physics - Section 3
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Mica sheets are used to provide structure for heating wire in heating elements and can withstand up to 900 °C.
Sheet mica is used principally in the electronic and electrical industries. Its usefulness in these applications is derived from its unique electrical and thermal insulating properties and its mechanical properties, which allow it to be cut, punched, stamped, and machined to close tolerances.
Specifically, mica is unusual in that it is a good electrical insulator at the same time as being a good thermal conductor. The leading use of block mica is as an electrical insulator in electronic equipment.
The SI unit of sound intensity is the watt per square metre.
Sound intensity is not the same physical quantity as sound pressure. Hearing is directly sensitive to sound pressure which is related to sound intensity.
In consumer audio electronics, the level differences are called "intensity" differences, but sound intensity is a specifically defined quantity and cannot be sensed by a simple microphone.
A rainbow is an optical and meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky.
It takes the form of a multi coloured arc. Rainbows caused by sunlight always appear in the section of sky directly opposite the sun.
Rainbows can be full circles; however, the average observer sees only an arc formed by illuminated droplets above the ground, and centred on a line from the sun to the observer's eye.
Mercury is commonly known as quicksilver.
A heavy, silvery d-block element, mercury is the only metallic element that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature.
Alpha Centauri or Toliman, is the brightest star in the southern constellation of Centaurus and the third brightest star in the night sky.
The Alpha Centauri system is located 1.34 parsecs or 4.37 light years from the Sun, making it the closest star system to our Solar System.
Although it appears to the unaided eye as a single object, Alpha Centauri is actually a binary star system whose combined visual magnitude of −0.27 makes it the third brightest star seen from Earth after the −1.46 magnitude Sirius and the −0.72 magnitude Canopus.
Optical fibres typically include a transparent core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fibre to act as a waveguide.
Fibres that support many propagation paths or transverse modes are called multi-mode fibres, while those that support a single mode are called single-mode fibres.
Multi-mode fibres generally have a wider core diameter and are used for short-distance communication links and for applications where high power must be transmitted.
Superconductors are also able to maintain a current with no applied voltage whatsoever, a property exploited in superconducting electromagnets such as those found in MRI machines.
Experiments have demonstrated that currents in superconducting coils can persist for years without any measurable degradation. Experimental evidence points to a current lifetime of at least 100,000 years.
Electromagnetic tensor (or Faraday's tensor) in electromagnetism.
Finite deformation tensors for describing deformations and strain tensor for strain in continuum mechanics.
Permittivity and electric susceptibility are tensors in anisotropic media.
The absence of electric field inside the charged conductors means that electric lines of force cannot enter the empty space of any hollow conductor. Thus hollow conductor can be used to acts as an electrostatic shield. So sensitive electric instruments can be saved from external electric fields by covering them with the ​hollow conductor.
It is the friction between the feet and the ground that helps us to walk. Without this friction we would slip and fall.