Electromagnetic Waves Lecture Notes (PHY2065)

🗒
Coulomb’s Law




1 q1 × q2
F=
4πϵ0 r 2

ϵ0 = 8.854 × 10−12 C 2 N −1 m−2

1
∼ 9 × 109 Nm2 C −2
4πϵ0

1 q1 q2
F12 = × e^12
4πϵ0 r 2
1 q1 q2
F12 = × r 12
4πϵ0 r 3




Coulomb’s Law 1

, Example of the inverse square law




Coulomb’s Law 2

, 🗒
The Electric Field
1 Q
E= × 2 × e^r
4πϵ0 r
1 Q
E= × 3 × r^
4πϵ0 r

Units of E are N
C or V
m




The Electric Field 1

, Length - strength of field

Direction - field direction

Concentric and radii increases in equal steps




The Electric Field 2