One of the disturbing problems students must face when studying electromagnetism is that they have to deal with two vector fields (electric and magnetic fields) with different properties. In fact the two fields follow different equations so that they must be different in general situations. We can somehow decrease the burden if we can show that the two fields are symmetric or analogous (in some intuitive sense) in some special situations.
In the present study, we examined the effect of acoustic range of electric-magnetic field (EMF) on the behavioral manifestation of seizure in genetically epilepsy-prone rats (GEPRs) of Krushinsky-Molodkina strain. A 5-days exposure to EMF (10000 -15000 Hz frequency, 1.5 m/Tesla, during 20 min) resulted in partial or complete suppression of behavior seizure activity in GEPRs. Besides, on the background of EMF the latency period of first wild run was increased. On the same conditions, duration of wild run decreased.
Electric and magnetic fields existed each time electricity is generated, transmitted or used. Power frequency magnetic fields are receiving growing attention in recent years due to concerns that exposure to magnetic fields might cause health effects . At the late 1970s, Wertheimer and Leeper showed that the children living near electric wiring configurations have increased risk of cancer . Therefore, many researchers have made a study to assess whether the exposure to extremely low frequency (ELF) electric and magnetic field (EMF) can adversely affect human health.
Both electric and magnetic forces have a key role in the operation of a cyclotron. A schematic drawing of a cyclotron is shown in Figure 29.27a. The charges move inside two semicircular containers D 1 and D 2 , referred to as dees, because of their shape like the letter D. A high-frequency alternating potential difference is applied to the dees, and a uniform magnetic field is directed perpendicular to them. A positive ion released at P near the center of the magnet in one dee moves in a semicircular path (indicated by the dashed red line in the drawing) and arrives back at the gap in a time interval T/2, where T is the time interval needed to make one complete trip around the two dees, given by Equation 29.15. The frequency of the applied potential differ- ence is adjusted so that the polarity of the dees is reversed in the same time interval during which the ion travels around one dee. If the applied potential difference is adjusted such that D 2 is at a lower electric potential than D 1 by an amount 0 V, the ion accelerates across the gap to D 2 and its kinetic energy increases by an amount q 0 V. It then moves around D 2 in a semicircular path of greater radius (because its speed has increased). After a time interval T/2, it again arrives at the gap between the dees. By this time, the polarity across the dees has again been reversed, and the ion is given another “kick” across the gap. The motion continues so that for each half-circle trip around one dee, the ion gains additional kinetic energy equal to q 0 V. When the radius of its path is nearly that of the dees, the energetic ion leaves the system through the exit slit. Note that the operation of the cyclotron is based on the fact that T is inde- pendent of the speed of the ion and of the radius of the circular path (Eq. 29.15).
61. Rail guns have been suggested for launching projectiles into space without chemical rockets, and for ground-to-air antimissile weapons of war. A tabletop model rail gun (Fig. P30.61) consists of two long parallel horizontal rails 3.50 cm apart, bridged by a bar BD of mass 3.00 g. The bar is originally at rest at the midpoint of the rails and is free to slide without friction. When the switch is closed, electric current is quickly established in the circuit ABCDEA. The rails and bar have low electric resistance, and the current is limited to a constant 24.0 A by the power supply. (a) Find the magnitude of the magnetic field 1.75 cm from a single very long straight wire carrying current 24.0 A. (b) Find the magnitude and direction of the magnetic field at point C in the diagram, the midpoint of the bar, immediately after the switch is closed. Suggestion: Consider what conclusions you can draw from the Biot–Savart law. (c) At other points along the bar BD, the field is in the same direction as at point C, but larger in magnitude. Assume that the average effective magnetic field along BD is five times larger than the field at C. With this assumption, find the magnitude and direction of the force on the bar. (d) Find the acceleration of the bar when it is in motion. (e) Does the bar move with constant acceleration? (f) Find the velocity of the bar after it has traveled 130 cm to the end of the rails.
PEC structure and vacuum structure are simulated accordingly. The detail simulation set-up for designing HIS can be found in [15, 16]. The reflection magnitude and the surface impedance of the designed AMC are then obtained by simulating a unit cell with electric and magnetic boundary condition at the vertical and horizontal walls as depicted in Figure 1(b).
This paper presents a method for inverting ground penetrating radargrams in terms of one-dimensional profiles. We resort to a special type of linearization of the damped E-field wave equation to solve the inverse problem. The numerical algorithm for the inversion is iterative and requires the solution of several forward problems, which we evaluate using the matrix propagation approach. Analytical expressions for the derivatives with respect to physical properties are obtained using the self-adjoint Green’s function method. We consider three physical properties of materials; namely dielectrical permittivity, magnetic permeability and electrical conductivity. The inverse problem is solved minimizing the quadratic norm of the residuals using quadratic programming optimization. In the iterative process to speed up convergence we use the Levenberg–Mardquardt method. The special type of linearization is based on an integral equation that involves derivatives of the electric field with respect to magnetic permeability, electrical conductivity and dielectric permittivity; this equation is the result of analyzing the implication of the scaling properties of the electromagnetic field. The ground is modeled using thin horizontal layers to approximate general variations of the physical properties. We show that standard synthetic radargrams due to dielectric permittivity contrasts can be matched using electrical conductivity or magnetic permeability variations. The results indicate that it is impossible to differentiate one property from the other using GPR data. q 2000 Elsevier Science B.V. All rights reserved.
The dotted curve in Fig. 3 describes the running of α −1 (µ) for monopolic “quark-leptons” created by preons which are bound by supersymmetric hyper-electric non-Abelian flux tubes. The curve AB corresponds to the region of spreon condensation, where we have both hyper- electric and hyper-magnetic strings. The point C corresponds to the second vacuum of our theory. For µ ≥ M f crit we have the running of monopole coupling constant. The corresponding
The RFID frequency lies under radio wave spectrum placed between the Electric waves and Infra-red in electromagnetic spectrum. The smallest frequency in radio wave is 9 KHz (very low frequency, VLF) and the highest frequency is 3000 GHz. However, the RFID frequency only categorized into four groups; low frequency (LF), high frequency (HF), ultra-high frequency (UHF) and super high frequency (SHF). The frequency band can be different in some frequency. For example the LF band in Europe is between 865-868 MHz while in North America is between 902 – 928 MHZ. Different frequency represent different ranges of detection. Adhering to the concept λ= 1/2Πf, means that at lower frequency band the range of detection is higher. However, it is difficult to design a system at low frequency due to size limitation. Figure 2.2 shows the frequency band for RFID in electromagnetic spectrum line.
keamanan kartu. Selain itu, perkembangan teknologi membutuhkan kartu agar dapat dibaca dan diproses menggunakan komputer. Perkembangan pertama yang cukup revolusioner adalah magnetic stripe pada bagian belakang kartu. Mungkin Anda sudah sangat hapal betul dengan garis blok hitam di bagian belakang.
This study investigates the use of computer simulation as a teaching aid in students’ understanding in learning the concepts of electric fields and electric forces. One hundred students were involved in the study that were classified as experimental group (EG) and control group (CG) by a lottery method. The two groups were taught the same topic for one week by the traditional lecture method for the control group and by the help of computer simulations for the experimental group. In addition, a pilot study was conducted at another school known as Tana Haik Senior Secondary School to test the validity and reliability of the instrument and to measure the background of the samples. Their achievements were measured using a test. A pre-test was given before treatment to know their performance level and pre-knowledge and a post test was administered after treatment to examine whether they showed a progress or not. Their achievement results were analyzed by using a t-test. The analysis of the result indicates that, students (EG) who were taught using computer simulations as a teaching aid showed a good progress than the control group.
Electric powertrain system has been sidelined since the emergence of the ICE car back in the early 20 th century. Recent oil crisis has sparked a lot of positive attention to the electric vehicle. Many organization and party has begun active in the scene of electric vehicle such as the various drag and racing electric vehicle competition to further enhance the public awareness of the forgotten technology.
Feromagnetik merupakan bahan yang memiliki nilai suseptibilitas magnetic χm Positif yang sangat tinggi.Dalam bahan ini sejumlah kecil medan magnetic luar dapat menyebabkan derajat penyerahan yang tinggi pada momen dipol magnetic atomnya.Dalam beberapa kasus,penyearahan ini dapat bertahan sekalipun medan pemagnetannya telah hilang.Ini terjadi karena momen dipol magnetic atom dari bahan-bahan feromagnetik ini mengarahkan gaya-gaya yang kuat pada atom tetangganya sehingga dalam daerah ruang yang sempit momen ini diserahkan ini disebut daerah magnetic.Dalam daerah ini,semua momen magnetic diserahkan,tetapi arah penyearahnya beragam dari daerah sehingga momen magnetic total dari kepingan mikroskopik bahan feromagnetik ini adalah nol dalam keadaan normal (willian, 2003).
Active solar region is generally manifest as appearance of sunspots. A group of sunspot which has complex structure both in magnetic polarities and has concentrated plasma confinement might be the region of potentially energy build-up and flare-strom productive region. A powerful X2.2 solar flare blasts towards Earth from sunspot number AR2297 or WK0049 number was erupting with M and C class flares before the magnetic energy finally gave way to the x-flare on 11 March 2015, causing HF radio blackouts.
reusable. Sangat prospektif apabila diaplikasikan pada industri kimia (Pospiskova and Safarik, 2013). Keunggulan lainnya, kitosan berukuran cukup kecil dan berasal dari material organic (bio) (Krajewska, 2004; Pillai, Paul and Sharma, 2009; Romo- sánchez et al., 2014; Liu et al., 2015). Hal tersebut berhubungan semakin luas sisi aktif enzim dan internal diffusion hindrance berkurang jika ukuran carrier enzim semakin kecil (Biró, Németh, et al., 2008). Kitosan terhitung cukup terjangkau, inert, hydrofilik, dan compatible sebagai matriks sehingga cocok untuk imobilisasi (Dittmann, 2000; Kumar and Wyman, 2009). Kitosan juga memiliki gugus amino memudahkan terjadinya ikatan kovalen (Krajewska, 2004; El-Ghaffar and Hashem, 2010; Santos-moriano, Woodley and Plou, 2016). Sehingga dalam penelitian ini akan digunakan hasil dari modifikasi kitosan menjadi magnetic kitosan, sebagai material support (matriks) dengan metode yang mengacu pada (El-Ghaffar and Hashem, 2010) dan (Pospiskova and Safarik, 2013).