Physics, Chemistry, Mathematics Forums

Dear Sir,
   I can't understand why we don't consider the energy due to 'point' charges.. ie, to say tht point charges don't have any 'self-energy'.  Since they produce an Electric Field then y do we neglect the energy stored in them.

Also, in this problem, we have a charge (q1) and a shell surrounding it with charge (q2), and we'r supposed to find the P.E. of system.
      Now, since the shell will have net charge (q1 +q2) on it's surface, i'll use energy density method and integrating from R->inf.  But answer requires a subtraction of "self-energy" of q1 which we are not supposed to take... I'm a little confused...can u please enlighten!!

MD

Hi,

I have this doubt in anal. geo. Hope some one could help me out.

The product of slopes of any two perpendicular lines is -1.Also slope of the x-axis is 0 and that of y-axis is infinity.Does this mean that 0 X infinity = -1 or this is just another meaningless eqn.

  

What are peracids and oxyacids ? what is the difference(or similarity) between them ?
can some1 clr my doubt

dear sir .i have one problem to be solved.
IF F(x) is increasing in [0,infinity]and G(x)is decreasing insame interval and H(x)=F{G(x)}and H(0)=O then prove that
H(x)is constant .

OETS Ques. Paper : Limits and continuity

ques. nos. : 7, 15, 19
Q 15 & Q 19 --- According to me f(f(f(x)))) should be equal to
x which is continous for all x. f(x)=1/(1-x).
am i wrong somewhere.

is there a short method for Q 7.

Find the area bounded by the curve y = 2x + x2 - x3 , the x-axis and the lines x=-1 and x=1
The graph of this curve is like a sinusoidal curve . In the –ve x-axis the curve lies below the x-axis and in the +ve x-axis it lies above . my doubt is if the curve lies below the x-axis should we take negative of the function ? How do we solve this problem ?

What does sinhx mean? I read it as sine of hyperbolic path of x or something in a book.What is its meaning and where does it find application?

what is binary system in mathematics?
please give a brief note

Can someone give me some hints on the solution of the following limit problems.

lim _{x to 0}{^{cub rt}(1+sinx)- ^{cub rt}(1-sinx)}/x

lim _{x to 0} {sin^-1 x-tan^-1 x}/x³

lim _{x to 0} { cos^-1(1-x)}/x

Let a_{1 =} 1 and a_n = n(a_n-1+1) for n=2,3,....

P_n = (1 + 1/a₁) (1 + 1/a₂) ......  (1 +  1/a_n)

Then lim_n->infinity P_n is ??