mintesnot

find the value of b such that u=(-2,4,2) ¡ì v=(b,b^2,1) are orthogonals.

two equal positive charges q are on the y axis,one at y=+a and the other at y=-a. a)show that the electric field on the x axis with < Ex=2kqx/(x^2+a^2)^3/2 > . b)show that near the origin,when x is much smaller than a,E,is approximately 2kqx/a^3.