Rotating magnetic field

The magnetic field rotates at a synchronous speed, so it should also rotate the rotor. But this is not so in an induction motor. During start-up, the rate of cutting of llux is the maximum and so is the induced e.m.f. in the rotor circuit. It diminishes with motor speed due to the reduced relative speed between the rotor and the stator flux. At a synchronous speed, there is no linkage of flux and thus no induced e.m.f. in the rotor circuit, consequently the torque developed is zero. 

The nuclear magnetic resonance phenomenon was first observed through a continuous wave experiment [2-6]. Resonance between the two Mj levels of an / = V2 nucleus (without loss of generality) in a magnetic field Bo can be achieved by applying a magnetic field rotating with a frequency (see Eqs. (1.12) and (1.16)) such that... 

Absorption of radiation giving rise to transitions between opposite spin orientations of unpaired electrons in a magnetic field Rotation of the plane polarized light by asymmetric molecules in solution without and with variation in wavelength... 

The chemical shift in a non-rotating single crystal depends on the orientation of the crystal with respect to the external magnetic field. Rotation of the sample, so effective in removing the effects of dipolar interaction, also averages... 

If we apply a magnetic field rotating at the Larmor frequency in the plane perpendicular to the static field, we can cause the individual nuclear moments to flip with the result that the entire macroscopic magnetization may be turned towards or away from the static field. In order to understand this and other more complicated operations, we now discuss the rotating frame representation of pulse NMR. The major problem in trying to visualize the motion of the magnetization in a static magnetic field is the fact that all motions towards... 

Spin coupling of unpaired electrons with an applied magnetic field Rotation of molecules Vibration of molecules Rotation/vibration of molecules Electronic transitions (some large molecules only) Electronic energy... 

The thermal conductivity of CeCoIns has been studied in a magnetic field rotating within the 2D planes (Izawa et al., 2001). These data clearly reveal fourfold symmetiy for the thermal conductivity and indicate that the symmetiy most likely belongs to dx -y implying that the anisotropic antiferromagnetic fluctuation is relevant to the superconductivity. Independent... 

B magnetic field, rotational constant, Virial coefficient c speed of light, Miller index... 

Fig. 3.13 Magnetic susceptibility of a sample suspended from a vertical fiber versus the angle (6) of an applied magnetic field rotating about the sample-suspension as axis. The common minimum Xil XII S then given by 3xa - 2xx. where Xav S given (as before) by (x r + x + X V3 [ColSO].

Measuring the torque on a sample of a nematic liquid crystal in a magnetic field rotating with an angular velocity smaller than the critical one represents a relatively simple method for the determination of the rotational viscosity coefficient. Below the critical angular velocity Eq. (24) is valid with 0 = F. Neither the phase lag F-0 nor the anisotropy of the magnetic susceptibility have to be known. This method will be thoroughly discussed in Chap. Ill, Sect. 2.6 of Vol. 2A of this Handbook. 

A magnetic field rotating in the xy plane leads to a rotation of the c director. The calculation is similar to that in the nematic phase. However, it has to be taken into account that the interaction with the magnetic field is different for the two phases. Principally, the magnetic susceptibility of an SmC phase is biaxial with the main susceptibilities parallel to n perpendicular to n in the layer plane Xi) perpendicular to these two directions iX3)- I good approximation X2 Xi assumed and... 

Rearranging Equation 5.13, the updated equation for the electric field at time step n from its value E" at the previous time step and magnetic-field rotation previous half... 

Figure 5.4 The coordinates and notation introduced to describe the alignment of the director n and magnetic field H in the Zwetkoff experiment. The nematic liquid crystal is contained in a cylinder of radius R and height L as shown. The magnetic field rotates with angular velocity u aroimd the 2-axis, with the phase angles for n and H being given by 0 and respectively.

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