Question

7. The three charges in the figure below are at the vertices of an isosceles triangle. Let q = 7.50 nC and calculate the electric potential at the midpoint of the base. 9 d2 di (Let di = 1.00 cm and d2 = 7.00 cm.) 8. Four point charges each having charge Q are located at the corners of a square having sides of length a. (a) Find a symbolic expression for the total electric potential at the center of the square due to the four charges (Use any variable or symbol stated above along with the following as necessary: ke.) (b) Find a symbolic expression for the work required to bring a fifth charge p from infinity to the center of the square (Use any variable or symbol stated above along with the following as necessary: ke.)

Answer 1

(7) The electric potential is

$V=V_{1}+V_{2}+V_{3}$

$V=\frac{kq_{1}}{r_{1}}+\frac{kq_{2}}{r_{2}}+\frac{kq_{3}}{r_{3}}$

$V=-\frac{kq}{d_{1}/2}-\frac{kq}{d_{1}/2}+\frac{kq}{\sqrt{d_{2}^{2}-(\frac{d_{1}}{2})^{2}}}$

$V=-\frac{4kq}{d_{1}}+\frac{kq}{\sqrt{d_{2}^{2}-(\frac{d_{1}}{2})^{2}}}$

$V=-\frac{4*9.*10^{9}*7.50*10^{-9}}{0.01}+\frac{9.*10^{9}*7.50*10^{-9}}{\sqrt{0.07^{2}-(\frac{0.01}{2})^{2}}}$

$V=-27000+966.76$

$V=-26033V$