Question

Two very long uniform lines of charge are parallel and are separated by 0.300 m. Each line of charge has charge per unit length +5.20 micro C/m.What magnitude of forcedoes one line of charge exert on a 0.0500-m section of the other line of charge?

Answer 1

0.0810N

Answer 2

 Electric field magnitude for an infinite wire (which is the same as a very long uniform line of charge): 

E = λ/(2π∊r) 

where 
λ is charge per unit length 
∊ is the vacuum permittivity constant of value 8.85 × 10⁻¹² m⁻³ kg⁻¹ s⁴A² 
r is the distance from wire 
L is length 

λ= Q/L 
Q = λL = 5.20*10⁻⁶ * 0.0500 = 2.6*10⁻⁷ C 

E = λ/(2π∊r) = 5.20*10⁻⁶ / (2*π*∊* 0.300) = 311715.9 N/C 

F = Q*E = 311715.9 * 2.6*10⁻⁷ = 0.0810 N