Asd Electrical Engineer

THE HONG KONG POLYTECHNIC UNIVERSITY DEPARTMENT OF ELECTRICAL ENGINEERING EE2011/2711 Applied electromagnetism Expt. No. 3 Field Plotting Using Conducting Paper Objectives: 1. 2. 3. lash-up: To obtain the plain stitch pattern for a three-phase busbar correspondence at selected time instants during the cycle. To familiarize with field plotting using conducting report card and smooth-spoken paint. To obtain electrical parameters from field plots. Field-plotting kit (including sheets of carbon-loaded conducting paper, currency paint, connecting wires and sweeping pen) or PASCO Equipotential and Field Mapper; Variable dc power supply; Potential-divider (formed by connecting resistors on a breadboard); digital multimeter. Theory: Equipotentials and Curvilinear Squ ars It is evident that along an equipotential lift in that respect can be no electric field (since E = - dV/dx). It follows that a flux density line moldiness meet an equipotential surface at right angles. Consider a scurvy divisor of an electric field as shown in Fig. 1, where a1 and a2 are dickens equipotential surfaces, X1, X2, X3 and X4 are four electric flux lines. x1 x2 dy d? a2 a1 V V + dV Figure 1 X dx x4 x3 dz d? 1 The get flux passing done a1 is: d? ? D ? dA where D is the electric flux density of area a1.

(1) According to Gausss Law, the surface organic of the electric flux density must equal the sum charge enclosed: Q ? ? ? ? D ? dA (2) mental magnate C ? dQ D ? dzdy D ? dz ? dy dy dy ? ? ? ? 0? r dz ? ? ?dz ? dV dV E ? dx dx dx (3) where ?0 = 8.85 ? 10- 12 F/m is the permittivity of free space and! ?r is the relative permittivity of the dielectric. If we can choke equipotentials and flux lines such that they form curving squares (squares with curved sides (see Fig. 2), thus dy and dx are equal and the capacitance of each curved square (or cell) will be ?dz. In the system shown in Fig. 2, the dielectric may be considered to be made up of a large number of such cells in nonparallel publication and...If you want to get a full essay, send it on our website: BestEssayCheap.com

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