How can Coulomb's Law be used to find the force between a charge and a surface?

[shotikokobaxi]

Homework Statement

We have a charge Q and it's h metres far from the flat surface. Find the force with which acts on the Q charge by the surface
The answer is: F=kQ²/4h² i couldn't get it, please help me.

Homework Equations

The Attempt at a Solution

 

[gneill]

Homework Statement

we have a charge Q and it's h metres far from the flat surface. Find the force with which acts on the Q charge by the surface
The answer is: F=kQ²/4h² i couldn't get it, please help me

Wow! No need to shout (Big loud font)

Welcome to Physics Forums, shotikokobaxi.

What formula(s) are appropriate here? Is the flat surface a conducting surface? If so, what analysis technique is appropriate for calculating the effects of an induced charge?

 

[shotikokobaxi]

Wow! No need to shout (Big loud font)

Welcome to Physics Forums, shotikokobaxi.

What formula(s) are appropriate here? Is the flat surface a conducting surface? If so, what analysis technique is appropriate for calculating the effects of an induced charge?

we use kulon's force F=kq²/r² the question is to find the force with which the surface (which hasn't any charges) acts on the Q charge

 

[gneill]

we use kulon's force F=kq²/r² the question is to find the force with which the surface (which hasn't any charges) acts on the Q charge

Yes, that's what we call Coulomb's force law for electric charges. It is applicable, but there's a special technique which can be used for cases where one charge induces a charge in an otherwise uncharged conducting surface as you have here. Look up "the method of image charges".