Download presentation

Presentation is loading. Please wait.

Published byMercedes Jennison Modified over 3 years ago

1
Thermodynamics in static electric and magnetic fields 1 st law reads: -so far focus on PVT-systems where originates from mechanical work Now: -additional work terms for matter in fields Dielectric Materials 1 1 -electric field inside the capacitor: A + - VeVe dielectric material L +q -q -displacement field D given by the free charges on the capacitor plates: Source of D is density of free charges. Here: charge q on capacitor plate with area A

2
-Reduction of qEnergy content in capacitor reduced which means work W cap >0 done by the capacitor ( in accordance with our sign convention for PVT systems ) (dq 0 yields W cap >0) With V= volume of the dielectric material -When no material is present: still work is done by changing the field energy in the capacitor -Work done by the material exclusively: parameterized e.g., with time (slow changes!)

3
With Polarization=total dipole moment per volume With ( where V=const. is assumed so that PdV has not to be considered ) Comparing ( where work is done mechanically via volume change against P ) With we define the total dipole moment of the dielectric material with Correspondenceand

4
-Legendre transformations ( providing potentials depending on useful natural variables ) making electric field E variable H=H(S,E) making T variable G=G(T,E) and

5
Magnetic Materials 2 2 I N: # of turns of the wire R Faradays law: where Amperes law: where here A: cross sectional area of the ring magn. flux lines voltage V ind induced in 1 winding

6
-Reduction of the current Iwork done by the ring work done by the ring per time makes sure that reduction of B ( ) corresponds to work done by the ring -Again, when no material is present: still work is done on the source by changing the field energy In general: where M is the magnetization = magnetic dipole moment per volume No material M=0 rate at which work is done by the magnetic material

7
-Legendre transformations ( providing potentials depending on useful natural variables ) making magnetic field H variable H enth =H enth (S,H) making T variable G=G(T,H) and

Similar presentations

OK

Copyright © 2009 Pearson Education, Inc. Chapter 34 Electromagnetic Waves.

Copyright © 2009 Pearson Education, Inc. Chapter 34 Electromagnetic Waves.

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on electricity for grade 2 Ppt on heat treatment of steel Ppt on book review writing Ppt on food retailing in india Ppt on current account deficit in india Ppt on describing words for class 1 Business ppt on flipkart Ppt on chromosomes and genes labeling Ppt on industrial development in gujarat ahmedabad Ppt on different types of dance forms list