next up previous contents
Next: . Up: Electric Field Previous: Electric Field   Contents

.

\begin{figure}\centerline{ \psfig{file=problems/prob_1_1.eps,height=2.5in} }\end{figure}

Charges of $+q$ are located at the two bottom corners of an equilateral triangle with sides of length $a$. A charge of $-2q$ is at that top corner. This arrangement of charge can be considered two dipoles oriented at $60^\circ$ with respect to one another.

a) Find the electric field (magnitude and direction) at an arbitrary point on the y-axis above/outside the triangle.

b) What are the first two terms in the binomial-theorem-derived series for the electric field evaluated far from the charges, i.e. - for $y >> a$1?

\begin{figure}\centerline{ \psfig{file=problems/prob_1_2.eps,height=2.5in} }\end{figure}

Charges of $-q$ are located at both $y = a$ and $y = -a$, and a charge of $+2q$ is located at $y = 0$ on the y-axis. This arrangement of charge can be visualized as two opposing dipoles.

a) Find the electric field (magnitude and direction) at an arbitrary point on the x-axis.

b) What is nonzero term in the expansion of the electric field evaluated far from the charges, i.e. - for $x >> a$? Your answer should be a series of terms in inverse powers of $x$.

next up previous contents
Next: . Up: Electric Field Previous: Electric Field   Contents
Robert G. Brown 2003-02-09