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# [전자기학]Purcell 전자기학 연습문제

저작시기 2006.06 |등록일 2006.06.22 한글 (hwp) | 6페이지 | 무료

## 소개글

Berkeley physics course Vol.2
electricity and magnetism
저자 : Purcell
연습문제 6.14 , 7.14 , 9.8 , 9.10 , 11.7 , 11.23

## 목차

연습문제 6.14 , 7.14 , 9.8 , 9.10 , 11.7 , 11.23

## 본문내용

<6. 14> A coil is wound evenly on a torus of rectangular cross section. There are N turns of wire in all. Only a few are shown in the figure. With so many turns, we shall assume that the current on the surface of the torus flows exactly radially on the annular end faces, and exactly longitudinally on the inner and outer cylindrical surfaces. First convince yourself that on this assumption symmetry requires that the magnetic field everywhere should point in a "circumferential" direction, that is, that all field lines are circles about the axis of the torus. Second, prove that the field is zero at all points outside the torus, including the interior of the central hole. Third, find the magnitude of the field inside the torus, as a function of radius.

<7. 14> A metal crossbar of mass m slides without friction on two long parallel conducting rails a distance b apart. A resistor R is connected across the rails at one end; compared with R, the resistance of bar and rails is negligible. There is a uniform field B perpendicular to the plane of the figure. At time t=0 the crossbar is given a velocity v0 toward the right. What happens then?
(a) Does the rod ever stop moving? If so when?
(b) How far does it go?
(c) How about conservation of energy?