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The first STEM was built in 1938 by Baron Manfred von Ardenne, [2] [3] working in Berlin for Siemens.However, at the time the results were inferior to those of transmission electron microscopy, and von Ardenne only spent two years working on the problem.
The FBISE was established under the FBISE Act 1975. [2] It is an autonomous body of working under the Ministry of Federal Education and Professional Training. [3] The official website of FBISE was launched on June 7, 2001, and was inaugurated by Mrs. Zobaida Jalal, the Minister for Education [4] The first-ever online result of FBISE was announced on 18 August 2001. [5]
The Coulomb gauge (also known as the transverse gauge) is used in quantum chemistry and condensed matter physics and is defined by the gauge condition (more precisely, gauge fixing condition) (,) =. It is particularly useful for "semi-classical" calculations in quantum mechanics, in which the vector potential is quantized but the Coulomb ...
The concept and the name of gauge theory derives from the work of Hermann Weyl in 1918. [1] Weyl, in an attempt to generalize the geometrical ideas of general relativity to include electromagnetism, conjectured that Eichinvarianz or invariance under the change of scale (or "gauge") might also be a local symmetry of general relativity.
In physics, the observer effect is the disturbance of an observed system by the act of observation. [1] [2] This is often the result of utilising instruments that, by necessity, alter the state of what they measure in some manner. A common example is checking the pressure in an automobile tire, which causes some of the air to escape, thereby ...
The first edition of the book to bear the title Fundamentals of Physics, first published in 1970, was revised from the original text by Farrell Edwards and John J. Merrill. [2] (Editions for sale outside the USA have the title Principles of Physics.) Walker has been the revising author since 1990. [3]
The energy difference Lamb and Retherford found was a rise of about 1000 MHz (0.03 cm −1) of the 2 S 1/2 level above the 2 P 1/2 level. This particular difference is a one-loop effect of quantum electrodynamics , and can be interpreted as the influence of virtual photons that have been emitted and re-absorbed by the atom.
Particle physics or high-energy physics is the study of fundamental particles and forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the scale of protons and neutrons , while the study of combination of protons and neutrons is called nuclear physics .