Solución
E
=
c
∣
r
∣
2
=
c
∣
r
∣
r
∣
r
∣
E = \frac{c}{|r|^2} = \frac{c}{|r|}\frac{r}{|r|}
E
=
∣
r
∣
2
c
=
∣
r
∣
c
∣
r
∣
r