Estimate its capacitance to earth

[Ripperbat]

Homework Statement

A telephone wire of diameter 1mm is suspended 10m above the ground. Estimate its capacitance to Earth per unit length

Homework Equations

The Attempt at a Solution

I've tried to solve the problem by using the formula for a cylindrical capacitor and got the answer but apparently it was wrong. Instead it's supposed to be solved by the mirroing method. So now I'm lost. Help me please :)

Thx

 

[Spinnor]

Homework Statement

A telephone wire of diameter 1mm is suspended 10m above the ground. Estimate its capacitance to Earth per unit length

Homework Equations

The Attempt at a Solution

I've tried to solve the problem by using the formula for a cylindrical capacitor and got the answer but apparently it was wrong. Instead it's supposed to be solved by the mirroing method. So now I'm lost. Help me please :)

Thx

Consider two parallel 1mm thick wires a distance 20m apart with opposite charges, same electric field for the above problem. Does that make things easier? I'm not sure.