three identical positive charges Q are arranged at the vertices of an equilateral triangle..the side of the triangle is a..find the intensity of the field at the vertex of a regular tetrahedran of which the triangle is the base...

Question

three identical positive charges Q are arranged at the vertices of an equilateral triangle..the side of the triangle is a..find the intensity of the field at the vertex of  a regular tetrahedran of which the triangle is the base...

anonymous · Answer

|dw:1334837813758:dw|
since the charge distribution is symmetric about the axis the net E field is
$$E(total)=3Ecos30$$
            $$=3(\sqrt{3}/2)*(1/4\Pi \epsilon0)*q/a^2$$
$$=[27\sqrt{3}/2]*10^{9}q/a ^{2}$$