Magnetic field, definition

Early reports of silicon NMR data employ the magnetic field definition of chemical shifts instead of... 

Now the effective conductivity ia the direction of the electric field is <7/(1 + /5 ), ie, the scalar conductivity reduced by a factor of (1 + /5 ) by the magnetic field. Also, the electric current no longer flows in the direction of the electric field a component j exists which is perpendicular to both the electric and magnetic fields. This is the Hall current. The conductivity in the direction of the Hall current is greater by a factor of P than the conductivity in the direction of the electric field. The calculation of the scalar conductivity starts from its definition ... 

In 1903, Rutherford and associates were finally able to deflect the a-rays by electric and magnetic fields, showing that these are positively charged. Measurement of the charge-to-mass ratio indicated that a-rays were of atomic dimensions. In 1908 definitive experiments showed a-rays to be doubly chaiged helium atoms, ie, helium nuclei. 

Fig. 4.16 Definition of the polar angles 9, c(). k is the wave vector of the emitted y-ray. The z-axis may be defined by the direction of a magnetic field...

The magnetic field seen by the probe neutron is solely due to the magnetic dipole moment density of the unpaired electrons. In other words, the magnetisation density is simply related to the electron spin density by a multiplicative factor, and there is no ambiguity in its definition. 

To illustrate the use of the vector operators described in the previous section, consider the equations of Maxwell. In a vacuum they provide the basic description of an electromagnetic field in terms of the vector quantifies the electric field and 9C the magnetic field The definition of the field in a dielectric medium requires the introduction of two additional quantities, the electric displacement SH and the magnetic induction. The macroscopic electromagnetic properties of the medium are then determined by Maxwell s equations, viz. 

A diamagnetic body such as a droplet of water has, by its very definition, negative magnetic susceptibility. In the presence of a magnetic field, a force acts on the body when the scale of the magnetic-field... 

Figure 8.6 shows the definition of transition temperature Tc and transition width Wc. To remark how the purity of the material and the magnetic field influence the two parameters, we will report hereafter the measurements of the superconducting transition of titanium samples of different purity and in the presence of different magnetic fields. The transitions of four Ti samples, whose characteristics are reported in Table 8.12, are shown in Fig. 8.7 where a change of only 0.2% in purity dramatically moves both the transition... 

Even if nowadays, the MCT may be considered a primary thermometer only on a narrow temperature range, it is considered the best dissemination standard in the millikelvin range [56-59], In fact, the 3He melting pressure is a good thermometric property because of its sensitivity over three decades of temperature with a resolution A T/T up to 10 5 [56], The good repeatability, the insensitivity to magnetic fields up to 0.5 T [60] and the presence of temperature-fixed points allow for the control of possible shifts in the calibration curve of the pressure transducer. The usefulness of these fixed points is evident, considering that the ITS-90 is based just on the definition of fixed points. 

It is also possible to represent the electric and magnetic fields corresponding to a photon state of definite momentum p and polarization p. The expressions are16... 

In Fig. 11 the change in the junction resistance (at 2 mV) is plotted as an external magnetic field which goes from 1,500 to —1,500 Oe (circles) and is then reversed from —1,500 to 1,500 Oe (triangles) with the sample held at 80 K. When the magnetic field is between 20 and 200 Oe, the magnetization direction of the LSMO layer becomes antiparaUel to the Co layer. Using the conventional definition of MR, defined as AR/R p = (Rap p)/ ap> where Rap is the junction resistance in... 

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