Problem 13.24

จาก \(\vec{E} = \vec{E}_{+}+ \vec{E}_{-}\)

îĵîĵ

\(\vec{E} =\frac{kq}{r^{2}}(\cos \theta _{x}+ \sin \theta _{x}) +\frac{kq}{r^{2}}(\cos \theta _{x}- \sin \theta _{x})\)

î

\(\vec{E} = 2\frac{kq}{r^{2}}\cos \theta _{x}\)

î

\(\vec{E} = 2\frac{kq}{r^{2}}(\frac{r}{2r})\)

î

\(\vec{E} =\frac{kq}{r^{2}}\)

\(|\vec{E}| =\frac{kq}{r^{2}}\;\blacksquare\)