Here are my solutions to various problems in David J. Griffiths’s excellent textbook *Introduction to Electrodynamics, Third Edition*. Obviously I can’t offer any guarantee that all the solutions are actually *correct*, but I’ve given them my best shot.

After some consideration, I’ve decided to repost this index to the solutions. I understand that some folks may be concerned that I am providing ‘free’ answers to problems that some students have been assigned as homework, but there are several points that should be made:

- First, solutions to the problems in Griffiths’s textbooks are already readily available on the internet, as a cursory search with Google will reveal, so I’m not giving away anything that isn’t easily obtained by other means. Many of these solutions are provided by professors for their own courses.
- If a teacher is concerned about students copying answers from the internet, s/he should consider making up their own problems. I did this for the courses that I taught in my 25 years as a university lecturer. For a field as rich as physics, it shouldn’t be too difficult to come up with original problems.
- If you’re a student seeking to copy solutions, you should realize that you won’t learn much unless you make a genuine effort to solve the problem on your own first. Remember that in most universities, the majority of the marks for a course are obtained from exams, and if you sit an exam without having worked out problems on your own beforehand, your chances of passing are pretty low. In my experience as a teacher myself, I found that most students realize this and do make a genuine effort to learn the material on their own.
- Finally, judging by many comments I have received, my posts have provided many readers with different (and hopefully in many cases, clearer) explanations of sometimes difficult concepts, so their value goes beyond merely providing solutions to a few textbook problems. In most of my posts, I have tried to provide an explanation of the theory behind the problem in a way that makes sense to me, which usually involves filling in steps sometimes omitted in the textbooks.

**These solutions are the only ones that I’ve worked out so far, so please don’t ask me to post “the rest of the chapters” as I haven’t worked on those yet. I will get to them eventually.**

There is an official site listing errata in the textbook. If you’re confused by something in the text itself, it’s worth having a look here to see if there is a typo on that page.

**Chapter 1 – Vector analysis**

**Chapter 2 – Electrostatics**

2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.11, 2.12, 2.13, 2.14, 2.15, 2.16, 2.17, 2.18, 2.20, 2.21, 2.22, 2.23, 2.24, 2.25, 2.26, 2.27, 2.28, 2.30, 2.31, 2.32, 2.33, 2.35, 2.36, 2.37, 2.38, 2.39, 2.40, 2.41, 2.42, 2.43, 2.44, 2.46, 2.47, 2.48, 2.49, 2.50

**Chapter 3 – Special Techniques**

3.1, 3.6, 3.7, 3.10, 3.11, 3.12, 3.13, 3.14, 3.15, 3.17, 3.18(a), 3.18(b), 3.19, 3.21, 3.22, 3.23, 3.24, 3.25, 3.26, 3.27, 3.28, 3.29, 3.33, 3.34, 3.35, 3.36, 3.37, 3.38, 3.39, 3.40, 3.41, 3.42, 3.43, 3.44, 3.45, 3.46, 3.47, 3.48a

**Chapter 4 – Electric Fields in Matter**

4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 4.10, 4.11, 4.12, 4.13, 4.14, 4.15, 4.16, 4.18, 4.19, 4.20, 4.21, 4.22, 4.23, 4.24, 4.25, 4.26, 4.27, 4.28, 4.29, 4.30, 4.31, 4.32, 4.33, 4.34, 4.35, 4.36, 4.37, 4.38, 4.39, 4.40

**Chapter 5 – Magnetostatics**

5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 5.10, 5.11, 5.12, 5.13, 5.14, 5.15, 5.16, 5.17, 5.18, 5.19, 5.20, 5.21, 5.22, 5.23, 5.24, 5.25, 5.26, 5.27, 5.28, 5.29, 5.30, 5.31, 5.32, 5.33, 5.34, 5.35, 5.36, 5.37, 5.38, 5.39, 5.40, 5.41, 5.42, 5.43, 5.44, 5.45, 5.46, 5.47, 5.48, 5.49, 5.50a, 5.51, 5.52, 5.53, 5.54, 5.55, 5.56, 5.57, 5.58, 5.59, 5.60, 5.61

**Chapter 6 – Magnetic Fields in Matter**

6.1, 6.2, 6.3, 6.4, 6.5, 6.7, 6.8, 6.9, 6.10, 6.11, 6.12, 6.13, 6.15, 6.16, 6.17, 6.18, 6.19, 6.21, 6.22, 6.23, 6.24, 6.25, 6.26, 6.27, 6.28

**Chapter 7 – Electrodynamics**

7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 7.10, 7.11, 7.12, 7.13, 7.14, 7.15, 7.16, 7.17, 7.18, 7.19, 7.20, 7.21, 7.22, 7.23, 7.24, 7.25, 7.26, 7.27, 7.28, 7.29, 7.30, 7.31, 7.32, 7.33, 7.34, 7.35, 7.36, 7.37, 7.38, 7.39, 7.40, 7.41, 7.43, 7.44, 7.45, 7.46, 7.47, 7.48, 7.49, 7.50, 7.51, 7.52, 7.53, 7.54, 7.55, 7.56, 7.57, 7.58, 7.59, 7.60

**Chapter 8 – Conservation Laws**

8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 8.10, 8.11, 8.12, 8.13, 8.14

**Chapter 9 – Electromagnetic Waves**

9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 9.10, 9.11, 9.12, 9.13, 9.14, 9.15, 9.16, 9.17, 9.18a, 9.18b-c, 9.19a-b, 9.19c, 9.20, 9.21, 9.22, 9.23a, 9.23b, 9.24, 9.25, 9.26, 9.27, 9.28, 9.29, 9.30, 9.31, 9.32, 9.33, 9.34, 9.35, 9.36, 9.37, 9.38

**Chapter 10 – Potentials and Fields**

10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 10.10, 10.11, 10.12, 10.13, 10.14, 10.15, 10.16, 10.17, 10.18, 10.19, 10.20, 10.21, 10.22, 10.23, 10.24, 10.25, 10.26

**Chapter 11 – Radiation**

11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 11.10, 11.11, 11.12, 11.13, 11.14, 11.15, 11.16, 11.17, 11.18, 11.19, 11.20, 11.21, 11.22, 11.23, 11.24, 11.25, 11.26, 11.27, 11.28, 11.29, 11.30a, 11.30b, 11.31

**Chapter 12 – Electrodynamics and Relativity**

12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 12.10, 12.11, 12.12, 12.13, 12.14, 12.15, 12.16, 12.17, 12.18, 12.19, 12.20, 12.21, 12.22, 12.23, 12.24, 12.25, 12.26, 12.27, 12.28, 12.29, 12.30, 12.31, 12.32, 12.33, 12.34, 12.35, 12.36, 12.37, 12.38, 12.39, 12.40, 12.41, 12.42, 12.43, 12.44, 12.45, 12.46, 12.47, 12.48, 12.49, 12.50, 12.51, 12.52, 12.53, 12.54, 12.55, 12.56, 12.57, 12.58, 12.59, 12.60, 12.61

aliThank you very much……! It’s great…..!

Abhilash Sharmaits nice..

one thing, soln of prob. 2.9 and 2.10 are not given though they r easy , but (b) part of 2.9 is very conceptual so upload that also…

Jerrydo you have the rest of the chapters?

this is a life saver!

growescienceNot yet – will get there eventually.

AnonymousSounds good, your explanations are very succinct and clear, many thanks!

Parmar DigneshPlese,upload chap 1 solution.

Parmar DigneshPlese,upload chap 1 solution.

Rafi Ullah Afridivery good, specially your explanation of problems.

plZ upload chapter 6

AnonymousInfact there is an instructor’s solution manual .But there is a mistake in it 2.1

But u didnt workout it here

Aleshai’d

be interested to hear what you think the mistake is in 2.1.

Nick The Greekthe mistake that he is talking about I think……..if you check Griffith’s solutions manual,it is written,that the net force (its direction) is pointing towords the missing q……but that is not true in the general situation.I mean it could be towards the other way…..it depends on the signs of the charges…..in the problem,we know that q is positive, but we dont the sign of Q

Nick The Greeksorry I meant towards*

ashokinterested in chapters 7 to 12

JerryThese solutions are very very helpful to me, you’ve explained it vary well.

Viktor.GGood job fella , I am waiting (unpatiently) for the rest chapters . Heil Sagan.

JerryFive chapters yet?

Please carry on with the good job, they’d been of great help to me.

Anonymoussalamuna, You explain it very well.thank you very much

Salma Ahmadplease upload the solution of problem 3.10 chapter special techniques.

growescienceI’ve now posted this one.

georgianajackalHey sulu did u get any help?

AnonymousHas anyone worked through the many parts of problem 2.54? I would really appreciate if someone could help out with them, in particular part g.

These solutions have been incredibly helpful otherwise. Thanks!

growescienceThere are only 51 problems in chapter 2 (in the third edition). What edition are you using?

AnonymousAhhh, my mistake. I was looking at the wrong edition. It turns out 2.54 in the 4th ed. is just about the same as 2.49 in the 3rd. Thanks for pointing out the mix-up!

Anonymousyour method of explaining the concepts and the underlying reason of the maths is wonderful….GREAT JOB SIR!!!

AnonymousThanks for maintaining this site! Much better than a solutions manual because you actually explain why you do what you do–so it’s possible to follow along and actually learn from the problems. I used your solutions for Griffiths’ Quantum Mechanics too!

koushikI find the explanation to the solution really helpful. Million thanks for your effort in publishing this content.

AnonymousThese are really very well done. Kudos and thanks!

Anonymousits awesome !!!!!

mithilesh kumarthanks,this is really halpfull

Anonymousthank u so much

lukaIt is really helpful.. Thank u so much.thank u.

ChristianHi, do you have the solution to the 8.9 Problem from the 4th Edition. I have my solution but I need to compare with someone.

growescienceSorry, I don’t have the 4th edition.

AnonymousThank you so much for explaining the problems! It is a great help!

AnonymousGreat initiative. Thanks! 🙂

junku901Thank you so much. It is awesome!!

4749Thank you so much..

AnonymousAwesome job!

Really appreciate it!

AnonymousAwesome!!!

really helpful

I guess I can pass the object now!!

Rocio RiveraTHANK YOU VERY MUCH!!!!!!!!!!!!!!!!!!!!!!!

May God bless you for helping other people learn physics 🙂

growescienceYou’re welcome. Glad you enjoy the blog.

AnonymousThanks!!! Very Helpfull!!!!

darmudasiramazing task ,very helpful

AnonymousWonderful blog! It is invaluable to me, thank you!

AnonymousCan never thank you enough <3

David DorenfeldVery helpful. Especially like the cross-referencing to other posts and the review of the theory before getting into the problem solution. Excellent.

SteveThank you very much!!! But could you please solve the problem 2.40 of the 4th edition? THANK YOU!!

growescienceI’ve added 2.40 from the third edition (I don’t have the 4th edition, but the problem is probably the same).

Don’t know how I missed that one.

Anonymousthanks a lot for u r kind help

FREDDY PIOPOThankyou very much………….Its helps me alot as I am a bebinner in physics. very helpfull than any other wensite in terms of problem solving.

karulgI usually use the official solution manuel, but for some of the problems i needed (more) explnations to really understand them. Thanks a lot.

growescienceGlad you find it useful.

growescienceGlad you find it useful.

MahendraThank You very much it helps me alot .

darmudasirimagine a uniform magnetic field , pointing in z direction and filling all the space .A positive charge isat rest ,.Now if magnetic field is turned off ,in what direction does the charge move .plz explain

Hussain Ahmad Ahsanproud of you ….thank you so much

Brett TurnerThank you for these solutions and for the Quantum ones as well. Last year and the year before that I worked through every problem in the chapters that were relevant to the course. This would have been impossible with your solutions.

I still come back on occasion to look up solutions that have gotten fuzzy. I’m glad this resource still exists.

Brett Turner***without*** not with smh

Deng weichaoabout sec9.1 two-level sys. ,i can confirm that |ca|^2+|cb|^2=1 to first order in H’ from first-order approx..

but i can’t confirm that |ca|^2+|cb|^2 does =1 to second order in H’ from sec-order approx..is it possible to prove it?

Nimmy varkeyIt’s great, thank u so much

nadia alithanx a lot u released mine tesion 70 prcnt….God bless u…

JI would like something like a student manual, hints, mathematical advice; you may need to remember Bayes theorem for this problem, things like that, I don’t want to see the solution with all the solution with everything explained. Would be appreciated.

gwrowePost authorYou may find physicsforums helpful. You can ask specific questions there and get hints and suggestions for solving a problem.

jackCan anyone tell me the solution of problem, 2.10

SteveCwonderful stuff! thank you very much …