Problem $2\mathrm{.}2$

a$.$ Find the electric field $($magnitude and direction$)$ a distance $z$ above the midpoint between two equal charges, q $,$ a distance $d$ apart. Check that your result is consistent with what you'd expect when $zd.$

b$.$ Repeat part $($a$)$; only make the right$-$hand charge $-$q instead of $+$q this time.