The electric field strength E 0 is measured at a perpendicular distance R from an infinitely large, thin sheet that contains a uniform positive charge density σ . In terms of the stated properties and the permittivity of free space ε 0 , write an expression for the electric field strength E at a perpendicular distance 2 R from the sheet.

Electric Field Strength E₀ = E₀ = Constant

Explanation:

The Electric Filed Strength E₀ to an Infinite uniformly charge large sheet is constant how far is it i.e. it is independent of the distance away from the uniformly charge sheet.

Formula: E₀ = σ / 2 ε₀  

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.