Resolução - Halliday - Volume 3 - Eletricidade E Magnetismo - P23 014

Transcript

14. Since both charges are positive (and aligned along the z axis) we have  

q q 1

+ .
Enet
= 4πε0 (z − d/2)2 (z + d/2)2 For z  d we have (z ± d/2)−2 ≈ z −2 , so




Enet
≈ 1 q q 2q + . = 4πε0 z 2 z2 4πε0 z 2