15 HMK #4 Chp 25

15 HMK #4 Chp 25 - Ch. 25 PHYSICS 2B Spring 2011 Homework...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Ch. 25 PHYSICS 2B Spring 2011 Homework Solutions – Chapter 25 Author: Evan Grohs - [email protected] Ch. 25 Problems: 55, 58, 62, 64, 66, 68, 71, 74, 83, 86 Page 1/6
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Ch. 25 page 2/6 C URRENT , R ESISTANCE , AND E LECTROMOTIVE F ORCE 25.55. (a) I DENTIFY and S ET U P : Use . L R A E XECUTE :    2 3 8 0.104 1.25 10 m 3.65 10 m 14.0 m RA L    E VALUATE : This value is similar to that for good metallic conductors in Table 25.1. (b) I DENTIFY and S ET U P : Use V = EL to calculate E and then Ohm's law gives I. E XECUTE :   1.28 V/m 14.0 m 17.9 V VE L 17.9 V 172 A 0.104 V I R E VALUATE : We could do the calculation another way: 72 8 1.28 V/m so 3.51 10 A/m 3.65 10 m E EJ J 2 3 172 A, IJ A   which checks (c) I DENTIFY and S ET U P : Calculate / o r / JIA JE and then use Eq. (25.3) for the target variable d . v E XECUTE : dd J nqv nev 3 d 28 3 19 2.58 10 m/s 2.58 mm/s 8.5 10 m 1.602 10 C J v ne     E VALUATE : Even for this very large current the drift speed is small. 25.58. I DENTIFY : Conservation of charge requires that the current is the same in both sections. The voltage drops across each section add, so Cu Ag . R RR  The total resistance is the sum of the resistances of each section. I A , so , IR E L where R is the resistance of a section and L is its length. S ET U P : For copper, 8 Cu 1.72 10 m . For silver, 8 Ag 1.47 10 m. E XECUTE : (a) Cu Ag . VV I R 8 Cu Cu Cu 42 Cu (1.72 10 m)(0.8 m) 0.049 ( /4)(6.0 10 m) L R A and 8 Ag Ag Ag Ag (1.47 10 m)(1.2 m) 0.062 . (/ 4 ) ( 6 . 01 0 m ) L R A This gives 5.0 V 45 A. 0.049 0.062 I  The current in the copper wire is 45 A. (b) The current in the silver wire is 45 A, the same as that in the copper wire or else charge would build up at their interface.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/18/2011 for the course PHYS 2B 2b taught by Professor Hirsch during the Spring '10 term at UCSD.

Page1 / 6

15 HMK #4 Chp 25 - Ch. 25 PHYSICS 2B Spring 2011 Homework...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online