Question

Hi..., can you help me? please. I have 4 questions of Mathematical Physics. Please see the question in the image I upload. Thank you :)

Answer 1

For the first question , you need to take dot product with (BxC) on both sides of the equation . You must know the property that B.BxC) is 0 and ~ly C.(BxC) too is 0. The required is obtained in the very next step. Convey your doubts if any.

Answer 2

for the qs in second pic, I suggest you rather post it in maths. They appear to be lengthy, I'll give them a try later..

Answer 3

These are really good problems. What level course is this. Community college or university. Grad or undergrad? My advice, is to get a solutions manual or get other books which are very similar to your book and make sure those books have solutions manuals and then just start looking up similar problems. I'm trying to take a stab at your problems, but they are pretty hard.

Answer 4

@Kappa007: OOk thank you for your help ^^

Answer 5

@Fellowroot : yes.., this from arfken's book, mathematical method for physicist 6th edition. I'm currently studying Physics at University of Indonesia. undergrad program., :)

Answer 6

@Fellowroot : i'm sophomore :), and you?

Answer 7

what's dellxy ?

Answer 8

@kappa007 : its kronecker delta

Answer 9

thanks for that, I'm trying now..

Answer 10

there's an application of Vector triple product. Did you use that while attempting ?

Answer 11

15.15 done.

Answer 12

other 2 also done. :)

Answer 13

15.15 a) this is based on the fact : for 3 vectors a,b,c , b.(bxc) will always be 0 (since bxc is perpendicular to b)

15.15 b) just write the reciprocal vectors in terms of normal vectors and simplify using vector triple product formula.

15.15 c) this also needs vector triple product formula . Use stuff from b part.

15.16 assume r.h.s to be any vector x. Take dot product with ' a ' on both sides and then on comparing with a.a' = 1, you'll get the proof done.

15.17 this requires kronecker delta formula. You can do this again by assuming r.h.s to be a vector x and taking pre-dot as before with any one of a, b or c. It gets proved in the very next step.

Answer 14

what do you mean r.h.s???/

Answer 15

@Kappa007 What do you mean r.h.s?

Answer 16

right hand side

Answer 17

ohh ok.., thank you